Computer Basics PDF

A computer is an electronic device used for processing data Data are pieces of programs that have been properly prepared so that the machine can work with them. Computers can plot the course of rockets, prepare bank statements, predict election results, forecast weather conditions and perform many...

A computer is an electronic device used for processing data Data are pieces of programs that have been properly prepared so that the machine can work with them. Computers can plot the course of rockets, prepare bank statements, predict election results, forecast weather conditions and perform many other tasks. Many people believe that a computer is a very large information machine. The internal operations of a computer are called processing. Output consists of the results of processing data. Computers have circuits for performing arithmetic operations such as addition, subtraction, division , multiplication and exponentiation. In school terms, the subject matter is considered as input, the studying as processing, and the knowledge as output Many daily tasks can be viewed as process, that is, they can be worked out in a step-by-step process. Machines that are used in connection with the computer are called peripheral devices. Drilling for oil is a difficult Process  Mineral oil is very slippery, therefore, it acts as a good lubricant. To make some metals bright, one should...Heat..... them with special chemicals. The lack of grease in machines causes friction A great many people in the world depend upon oil lamps for illumination Oils of different grades are used for lubrication Steam condenses into water when it touches a cold surface. The tungsten wire inside an electric bulb sometimes vaporizes The crude oil is taken to the... refinery... to be treated Can anything Replace , a mother's love and care? In recent years, the speed at which civil engineering projects have been carried out has been vastly increased. Cranes require a tremendous variety of lifting Tackle The most noticeable property that affects a soil's behavior is its water content. Mild-steel bars are used in ordinary reinforced concrete beams to overcome the tensile weakness of concrete Concrete must be protected from freezing at least during the first seven days after placement Ground testing is essential in all foundation work. The art of metal working is developed into a science called metallurgy When the temperature is very high, a metal liquefies Metal workers know which ores can be smelted to change to metal. The inside of some furnaces is covered with firebricks The metal and slag are tapped out through the openings near the bottom of the furnace.  Men called gold and silver 'noble metals' because they do not tarnish when exposed to the atmosphere for a long time. Different metals are blended together to make alloys To make steel from iron it is necessary to increase the carbon content. The molten metal and the liquid slag in the furnace fall to the bottom of The hearth. The significant advantage associated with the use of microwaves for communications is their large bandwidth. To date, no complete waveguide communication system has been engineered and operated for commercial purposes.  Studies on microwave links have led to further research in microwave engineering. Just as sound travels through the air in waves, so does electricity in what we call radio waves. Astronomers use microwave frequencies to study electromagnetic radiations originating from stars. The number of times the current alternates decides the frequency or wave-length on which the station is broadcasting The open-wire telephone traffic is the oldest means of communication A modern broadcast transmitting station has an antenna from which sound waves combined with carrier waves are transmitted. Sound is made by vibrations and travels in waves. Microwave energy is also used for heating dielectric materials, The name radar has been derived from the initial letters of radio detecting and ranging. Radar denotes a method of scanning the surrounding space by means of high-frequency radio waves. The strength and direction of the reflected beam gives information on the size, distance, altitude, etc. of the object. When sufficient time has elapsed to permit the reception of echoes from the most distant objects of interest, the transmitter sends another short pulse. Radar systems calculate the distance of an object from the radar site by measuring the time a pulse of radio energy takes to travel to the object and back again. Electromagnetic energy covers the whole spectrum of energy which travels at approximately 3x100 meters per second. Radio energy is that part of the electromagnetic energy spectrum between about 1 mm and 100 kilometers wavelength Radar energy is that part of the radio energy spectrum between about 1 mm and 100 cm which is transmitted in a series of pulses of fairly short duration Electromagnetic energy from the transmitter is radiated from the aerial at regular intervals. The received signal, the echo, is displayed on the screen of the display unit. Portland cement concrete is foremost among the construction materials used in civil engineering projects In the past, concrete technology has been taught as an empirical science Concrete is a material that forms the basis of our modern buildings. From very early times, builders have tried to find materials that could be used to cement stones or bricks together. Lightweight aggregates can be either natural or synthetic materials. One of the advantages of concrete is its versatility not only as a building material but also as an architectural material. Formwork is a very important aspect of concrete construction. Today, synthetic fibers are produced in great quantities For a fiber or a finish to be truly functional, it must have the approval Of the consumer. Chemists prepare ingredients for a new fiber, and technologists process them. There are many fibrous structures in nature, but only those which can be spun into yarns suitable for weaving or knitting can be classified as textile fibers. When making very delicate materials, it may be necessary to use a yarn which is so fine that it would break down under the stresses imposed on it during manufacture. Asbestos is a mineral fiber that can be spun and made into fireproof fabrics or protective clothing Examples of animal fibers are mohair obtained from the Angora goat which originated in Turkey and cashmere from the Tibetan cashmere goat reared in China, northern India, and Iran. Cotton is the only vegetable fiber which consists of a single cell. The production of fibers flourishes where labor is cheap. The magnetic field increases with an increase in the current. Resistors are devices whereby resistance is interposed in a circuit. Generally speaking, mixtures of metals containing a magnetic substance have magnetic Properties The magnetic force of attraction is concentrated near the ends of the magnet. Generators are machines used for the large-scale production of electrical energy. A substance which is attracted by a magnet can itself be made into a magnet Unlike poles attract whereas like poles repel one another. If there is a potential difference between the ends of a conductor, a current will flow along it. In water turbines, the kinetic energy of running or falling water is converted into mechanical rotary motion. A nuclear reactor serves to convert nuclear energy into thermal energy The force of attraction exerted by the mass of the earth is called gravity When a force acts upon a rigid body, it is balanced by an equal reaction force acting in the opposite direction.  Energy is commonly defined as the capacity of a system to do work When a body escapes from gravity, it becomes weightless The downward force exerted by an object is the same as its weight. It is known that energy can be transformed. from one system to another. 7. Our existence depends upon the energy we receive from the sun. 8. Some of the students at the anthropology department will specialize in economic anthropology. 9. Her work is entirely mechanical, it does not involve imagination or innovation. 10. Most scientists think that water does not exist on the surface of the moon. 11. The science that deals with energy and forces and their effect on bodies is mechanics 12. Each department in a university has regulations of its own; in other words, each department has Special regulations. 1. In some countries, agricultural production has been mechanized. 2. The standard unit of mass is the kilogram; however we measure very small masses in grams 3....electric currents cannot flow easily in all substances. 4. Iran produces a large quantity of oil every day. 5. Copper allows electricity to flow easily through it. 6. Of all the metals, iron, cobalt, and nickel have the greatest magnetic properties. 7. A magnet produces a magnetic field in the space around it. 8. In physics, the researchers came within measurable, distance of success. 9. If we magnetize, an iron bar, the quality of attracting pieces of iron will be found at two regions at the ends of the bar. 10. Accurate measurement is essential for making good quality machines and parts. 11. The productive lands of Iran are mostly located in the Northern part of the country. 12. Scientists are experimenting on cars that run electrically 1. In addition to their speed, computers are accurate and can do repetitive operations over and over again without becoming tired or bored. 2. Several terminals can be added to a basic computer system if the need arises. 3. A trip around the world is an instructive experience. 4. After a long discussion, he was perfectly satisfied. 5. accuracy , is one of the advantages of using computers in research or in statistical analysis. 6. We were instructed to document our programs very carefully. 7. scientists are still trying to perfect the computer. 8. He studies four hours every day in addition to his daily work. 9. There is often no additional charge for the programs when buying a computer system. 10. The perfection of the design will take some more time. 11. Practice makes perfect 12. He gave us strict instruction to handle the instrument with care. 1. Looking thoughtfully, at me, the little boy asked my name. 2. The snow fell sufficiently and soon covered the ground. 3. TO illuminate the room, they used oil-burning lamps. 4. Do you think in English when you speak English? 5. Since the rooms were poorly illuminated, he preferred to study in the library 6. He often acts without thought 7. The mixture gradually thickened as the temperature changed. 8. One meal a day will not Suffice a growing boy. 9. The oil used for lubrication must be of the correct thickness 10. These newly-born babies are not in good physical condition; they are not sufficiently fed. 11. The walls were so thick that they were not destroyed by the bomb 12. Oil is also used for illumination since it burns brightly 13. He considers the consequences of his behavior or words. In other words, he is a thoughtful person 14. sufficient heat must be applied to melt the metal. 1. We practice economically when we avoid wasting money, water, food, electricity, energy, or any other resources. 2. His plan is excellent in theory but it would not succeed in practice. 3. Plants grow naturally in such a good climate. 4. The Construction. of several apartment buildings will ease the housing shortage. 5. He economized by taking a train instead of taking a taxi every time he went to school. 6. Man is engaged in a constant struggle with nature 7. This company plans to construct a new hotel in the heart of the town.  8. A person should appreciate receiving constructive criticism. 9. Geologists can theorize about the age of the earth. 10. Economics is the science of economic relations. 11. Everybody should work constructively to produce a better environment. 12. Wind, rain, thunder, and lightning are natural forces 1. The questions were not difficult. Therefore, the students answered them easily 2. metallic substances are good conductors of heat and electricity. 3. The color purple is a combination of red and blue. 4. If you increase the tension of a string, it will break. 5. A wire which is stretched tensely vibrates very well. 6. Iron, gold, silver, and aluminum are metal 7. The technician repaired the tape-recorder with great ease 8. Two atoms of hydrogen combine with one atom of oxygen to form water. 9. If the strings of a musical instrument are not stretched, you should tense them in order to play the instrument 10. There was a tense atmosphere; people had a feeling of nervous strain and an attitude of expectancy. 11. In industry, a certain substance, such as a carbon lamp-filament is sometimes metallize in order to be combined with a metal and be made almost metallic in its properties. 12. If math problems are easy, they will need only a little work, and the students will solve them without any difficulty or trouble. 1. Amplification of sound can be done by an instrument called amplifier. 2. Eye glasses are used to correct near-sightedness, far- sightedness, and other visual defects.  3. The mechanic bought the parts of the engine separately and put them together. 4. You may not expect good results if you don't Systematize your work, 5. Electrical waves are amplified before they are changed into sound or voice signals. 6. If you work systematically, you will make a good progress. 7. The students were divided into three separate groups. 8. amplified sounds can be heard at a greater distance. 9. I remember meeting the man two years ago, but I can't visualize him. 10. The Atlantic Ocean separate America from Europe. 11. Certain subjects should be taught visually using charts, slides, and other visual aids. 12. The system underlying modern physics is very interesting. 13. Progress and success depend on systematic work. 1. It is difficult for me to describe exactly how I felt after I won the prize. 2. Our professor's presence is required at the annual general assembly. 3. Those two parts may look the same in appearance, but they are different in essence 4. Our English teacher's relation with us is quite pleasant. 5. A kind of writing in which the writer gives impressions about the look, feel, sound, taste, and smell of things is referred to as descriptive writing. 6. Rice grows best in the northern part of Iran where rainfall is relatively abundant. 7. To generate large quantities of steam, a high rate of evaporation in the boiler is essential 8. In writing, good description requires careful observation and organization. 9. It is difficult to relate these results to any known cause. 10. One of my classmates wrote a descriptively accurate account of the properties of iron. The description was so clear that the teacher gave him the best mark. 11. Mr. Tehrani was unfortunately not present at the ceremony 12. After a long illness, the director presented himself at a meeting a week ago. 1. Because of the dense fog, we could not drive easily. 2. A tape recorder can be very useful in learning a foreign language. 3. Fever increases the body temperature. 4. Polite people do not behave coarsely 5. There has been a great increase in population during the past ten years. 6. Since fine and Coarse aggregates are batched separately, the grading of each type of aggregate should be known and controlled. 7. The density of the concrete varies with mix proportions. 8. It is necessary to know how to use electricity wisely and safely. 9. As we travel south, the weather becomes increasingly warm, 10. Aggregates are usually graded according to their coarseness, and fineness. 11. For our own safety, we should consider some of the dangers involved in the use of electricity 12.Some countries such as India are densely populated. 1. The efficiency of an engine depends on several mechanical factors. 2. Our professor needs an assistant,preferably one who is a college graduate. 3. preventive medicine protects us against diseases. 4. The generation of electric power is usually dependent upon the water supply of a dam. 5. The movement of laser beams differs from that of white rays. 6. A teacher should not show preference for any student, 7. Friction is prevented by lubrication. 8. A group of students went on a picnic, but Ali preferred to stay at home. 9. In order to have a machine function smoothly, its different parts should be lubricated properly. 10. The prevention of fires is a very serious and necessary business. 11. Sometimes scientists approach the same problem differently 12. A child's dependence, on his parents decreases as he grows older. 1. They have invented an instrument for measuring the pressure of liquids or gases. 2. Some of the special elements cannot be found in the pure state in nature. 3. If you press that button, a bell will ring. 4. We have a good specialist working with us in our field of study. 5. Farming is mechanized in order to increase the amount of grains produced. 6. When a man troubled or worried about a problem, he is sometimes unable to concentrate; therefore, he does his work mechanically. ((_1_)) A. Do the following exercises according to the explanations given in the Pre - Reading Part. 1. a. The machine broke with a sound which was frightening b. The machine broke with a frightening sound. 2. a. Last night we saw an unidentified object which was flying b. Last night we saw an unidentified flying object. 3. a. High buildings must be strong enough to resist the forces which are damaging b. High building must be strong enough to resist the damaging forces. 4. a. Induction motors operate through the medium of a magnetic field which is moving. b. Induction motors operate through the medium of a moving magnetic field. 5. a. Sound waves from an object which is vibrating move in every direction. b. Sound waves from a vibrating object move in every direction. 6. a. The needs which were growing for rubber were satisfied after synthetic rubber was produced. b. The growing needs for rubber were satisfied after synthetic rubber was produced. 7. a. The industrial areas which were developing were too far from the rubber plantations. b. The developing industrial areas were too far from the rubber plantations. B. Do the following exercises according to the explanations given in the Pre - Reading Part. 1. a. The plastic which is heated is injected into a mold and so takes its shape. b. The heated plastic is injected in to a mold and so takes its shape 2. a. In this area only water which is pumped is available. b. In this area only pumped water is available. 3. a. The original book is in English ; the one I have is a copy which is translated. b. The original book is in English ; The one I have is a translated copy. 4. a. Those cards which are punched are fed into the machine. b. Those punched cards are fed into the machine. 5. a. The clay that is compressed is strong enough to withstand great pressure. b. The compressed clay is strong enough to withstand great pressure. 6. a. The latex which has been dried is dispatched to other countries. b. The dried latex is dispatched to other countries. 7. a. The plantations which were established had to be in countries with a hot , humid climate. b. The established plantations had to be in countries with a hot , humid climate. C. Do the following exercises according to the explanations given in the Pre - Reading Part. 1. a. The exhaust steam is passed over tubes which are filled with cold water. b. The exhaust steam is passed over tubes filled with cold water. 2. a. The efficiency of an engine is the ratio of the work which is done to the heat which is received. b. The efficiency of an engine is the ratio of the work done to the heat receieved. 3. a. The power which is demanded from modern turbines is continually increasing. b. The power demanded from modern turbines is continually increasing. 4. a. The research which is being carried out on this subject is extensive. b. The research carried out on this subject is extensive. 5. a. The torque which is exerted on the crankshaft should be even. b. The torque exerted on the crankshaft should be even. 6. a. Generators which are not required for service are stopped. b. Generators not required for service are stopped. 7. a. Industry could not depend on supplies which were stopped by war or shipping troubles. b. Industry could not depend on supplies stopped by war or shipping troubles. D. Do the following exercises according to the explanations given in the Pre - Reading Part. 1. a. Coal miners produce millions of tons of coal every week. b. Millions of tones of coal are produced by coal miners every week. 2. a. Scientists know that matter is made up of very small particles. b. It is known by scientists that matter is made up of very small particles. 3. a. A skilled operator can carry out many operations on a lathe. b. Many operations can be carried out on a lathe by a skilled operater. 4. a. Mechanical devices harness various forms of energy. b. Various forms of energy are harnessed by mechanical devices. 5. a. Scientists call the form of energy stored in the molecules of some materials chemical energy b. The form of energy stored in the molecules of some materials is called chemical energy by scientists. 6. a. That country does not produce any heavy industrial machinery. b. Any heavy industrial machinery is not produced by that country. 7. a. The operator selected the appropriate gear for the job. b. The appropriate gear was selected by operator for the job. ((_2_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. He bought the watch. the watch was made in Switzerland. (know) b. He bought the watch but didn't know where it was made. 2. a. She heard the noise. The noise was made by a tractor. (realize) b. She heard the noise but didn't realize what made it. 3. a. We felt very cold. The cold came in from the open window upstairs. (find out) b. We felt very cold but didn't find out where it came in. 4. a. The workers welcomed the raise in salary. The raise was decided upon because the workers had worked hard. (know) b. The workers welcomed the raise in salary but didn't know why it raised. 5. a. Early men discovered fire. Fire was produced by lightning. (appreciate) b. Early men discovered fire, but didn't appreciate how it was produced. 6. a. The poor woman received some money every month. Her neighbors sent it. (discover) b. The poor woman recieved some money every month, but didn't discover who sent it. ((_3_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. Mathematics no longer interests him. It was once his favorite subject. b. Mathematics, once his favorite subject, no longer interests him. 2. a. Libya is a leading producer of oil. It is a country in North Africa. b. Libya, a country in North Africa, is a leading producer of oil. 3. a. Professor Nelson arrived in Iran yesterday. He is an expert in computer technology. b. Professor Nelson, an expert in computer technology, arived in Iran yesterday. 4. a. The volcano erupted again with great violence. It has been dormant for over a hundred years. b. The volcano, dormant for over a hundred years, erupted again with great violence. 5. a. Mr. Campbell was on television last night. He is the producer of International Business Machines. b. Mr. Campbell, the producer of International Business Machines, was on television last night. 6. a. Television brings the world into our homes in sight and sound. It is one of the wonders of electronics era. b. Television, one of the wonders of electronics era, brings the would into our homes in sight and sound. B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. Copper is flexible. Aluminum is flexible, too. b. Copper is as flexible as aluminum. 2. a. A bicycle is not complex in structure. A hovercraft is complex in structure. b. A bicycle is not as complex as a hovercraft in structure. 3. a. A jet plane is not very efficient at low speeds. A propeller-driven plane is efficient at low speeds. b. A jet plane is not as efficient as a propeller-driven plane at low speeds. 4. a. Impact printers are expensive. Non-impact printers are expensive, too. b. Impact printers are as expensive as non-impact printers. 5. a. The civil engineer recently employed is not qualified enough. Other engineers in the office are very qualified. b. The civil engineer recently employed is not as qualified as other engineers in the office. 6. a. Data preparation is important. Data Processing is important, too. b. Data preparation is as important as Data processing. ((_4_)) A. Do the following exercise according to the explanations given in the Pre-Reading Part. The crude oil which...is obtained… (obtain) from the oil well....is taken... (take) to the refinery. There it...is treated… (treat) with heat. The first vapors rising from it…are collected & cooled.. (collect and cool) to form petrol. The gas that... is obtained… (obtain) next …is condensed...(condense) into kerosene. Then oils of different grades…are produced… Witch…is used…(use) for lubrication.Last of all, a thick oil...is left behind... (leave behind), which..is burnt... (burn) as fuel. B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. If the steam……….(not be super heated), higher pressures are necessary. b. if the steam is not super heated, higher pressures are necessary. 2. a. The fuel…………..(ignite) spontaneously if it reaches the critical temperature. b. the fuel ignites spontaneously if it reaches the critical temperature. 3. a. If the combustion chamber………………(not be designed) properly, the mixture may ignites spontaneously. b. if the combustion chamber is not designed properly, the mixture may ignite spontaneously. 4. a. There will be appreciable heat loss if the gases……….. (be allowed) to escape unburnt. b. there will be appreciable heat loss if the gases are allowed to escape unburnt. 5. a. If the combustion gases............(not be diluted), the temperature at the turbine will be too high. b. if the combustion gases are not diluted, the temperature at the turbine will be too high. 6. a. If the water is not pure, it………….(need) further treatment. b. if the water is not pure, it needs further treatment. 7. a. Oil floats if you………..(pour) it on water. b. Oil floats if you pour it on water. 8. a. The bearings become overheated if the supply of lubricant………….(fail).. b. The bearings become overheated if the supply of lubricant fails. ((_5_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. They say that the Milky Way is the bright cloud of stars that stretches across the sky b. The milky way is said to be the bright cloud of stars that stretches across the sky. 2. a. Scientists have proved that the meteors are fragments of matter that enter the atmosphere of the earth at great speed. b. Meteors have been proved to be fragments of matter that enter the atmosphere of the earth at great speed. 3. a. We know that electronics is a relatively new branch of electrical engineering. b. Electronics is known to be relatively new branch of electrical engineering. 4. a. A scientist proved that the velocity of light is much greater than the velocity of sound. b. The velocity of light was proved to be much greater than the velocity of sound. 5. a. We know that mathematics, physics, and chemistry are necessary subjects for those who plan to study engineering. b. Mathematics, Physics and Chemistry are known to be necessary subjects for those who plan to study engineering. 6. a. People once thought the world was flat. b. The world once was thought to be flat. B. Do the following exercises according to the explanations given in the Pre-Reading Part. \ 1. a. The mechanical engineer is going to repaire the instrument. He has recently arrived. b. The mechanical engineer who has recently arrived is going to repair the instrument. 2. a. The mechanical engineer is going to repair the instrument. We are going to visit him. b. The mechanical engineer whom we are going to visit is going to repair the instrument. 3. a. Some Iranian engineers will design the power station in the country. They are specialists in their fields. b. Some Iranian engineers who are specialists in their fields will design the power station in the country. 4. a. Some Iranian engineers will design the power stations in the country. The government is going to employ the engineers. b. Some Iranian engineers whom the government is going to employ will design the power stations in the country. 5. a. The students will pass the exams. The students have studied very hard. b. The students who have studied very hard will pass the exams. 6. a. The students will pass the exams. Professor Tehrani has taught the students. b. The students whom professor Tehrani has taught will pass the exams. ((_6_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. Ignition can be produced by a spark. Ignition can be produced by compression of the mixture. b. Ignition can be produced either by a spark or by compression of the mixture. 2. a. Bearings can be lubricated by gravity feed Bearings can be lubricated by forced feed. b. Bearings can be lubricated either by gravity feed or by forced feed. 3. a. You can use steel to make blades. You can use aluminum alloy to make blades. b. You can use either steal or aluminum alloy to make blades. 4. a. The use of aluminum alloy is common in manufacturing gasoline engines. The use of magnesium alloy is common in manufacturing gasoline engines. b. The use of aluminum alloy or magnesium alloy is common in manufacturing gasoline engines. 5. a. You can listen to this program on S.W.1. You can listen to this program on S.W.2. b. You can listen to this program either on S.W. 1 or on S.W. 2. B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. matter which is not living. b. Non-living matter. 2. a. a substance which is not a conductor. b. Non-conductor substance. 3. a. a surface which does not reflect. b. Non-reflecting Surface. 4. a. a shape which is not spherical b. Non-spherical shape 5. a. a substance which is not acid b. Non-acid substance 6. a. an object which does not rotate. b. Non-rotating shape. 7. a. a substance which is not protein. b. Non-protein substance. ((_7_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. The productive capacity of a country depends on the level of its technology. The productive capacity of a country depends on its supplies for raw material and labor. b. The productive capacity of a country depends on the level of its technology as well as its supplies for raw material and labor. 2. a. Energy is derived from coal. Energy is derived from petroleum. b. Energy is derived from coal as weil as from petroleum. 3. a. Oil drives tanks, airplanes and warships. Oil drives motor-cars and diesel locomotives. b. Oil drives tanks, airplanes and warships as well as motor-cars and diesel locomotives. 4. a. Temperature may be measured in Fahrenheit scale. Temperature may be measured in Centigrade scale. b. Temperature may be measured in Fahrenheit scale as well as in centigrade scale. 5. a. At the center of each atom, there is the nucleus, in which protons are found. At the center of each atom, there is the nucleus, in which neutrons are found. b. At the center of each atom, there is the nucleus, in which protons as well as neutrons are found. B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. Two of the planets in the solar system are called Pluto and Mercury. Pluto is the farthest from, and Mercury is the nearest to the sun. b. Two of the planets in the solar system are called Pluto and Mercury the former is the farthest from, and the latter is the nearest to the sun. 2. a. An element is composed of similar atoms, and a compound is composed of different atoms. An element cannot be decomposed into other substances, but a compound can. b. An element is composed of similar atoms and a compound is composed of different atoms. The former can not be decomposed, but the latter can. 3. a. An atom of hydrogen possesses a single proton, whereas an atom of uranium possesses 92. Therefore, an atom of hydrogen is much lighter than an atom of uranium. b. An atom of hydrogen possesses a single proton, where as an atom of uranium possesses 92. The former is lighter than the latter. 4. a. A football will fall more slowly than a stone of the same size because the football has a lower density than the stone. b. A football will fall more slowly than a stone of the same size, because the former has a lower density than the latter. 5. a. The nucleus of an atom is mainly composed of protons and neutrons. Protons carry a positive charge, while neutrons have no electric charge. b. The nucleus of an atom is mainly composed of protons and neutrons. The former carries a positive charge, but the latter has no electric charge. 6. a. Thunder and lightning occur simultaneously, but at a distance lightning can be seen before the thunder can be heard. b. Thunder and lightning occur simultaneously. The latter can be seen before the former can be heard. 7. a. We now recognize two kinds of electricity: static electricity and current electricity. Static electricity is stationary electricity, while current electricity is electricity in motion. b. We now recognize two kinds of electricity: static electricity and current electricity. The former is stationary electricity and the latter is electricity in motion. 8. a. Ali and Ahmad go to the university, Ali studies chemistry and Ahmad is a student of mathematics. b. Ali and Ahmad go to university, the former studies chemistry and the latter is a student of mathematics. 9. a. In any magnet there is a south pole and a north pole. The south pole repels all other south poles and the north pole repels all other north poles. b. In any magnet there is a south pole and a north pole. The former repels all other south poles and the latter repels all other north poles. ((_8_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. Building this house will cost you a lot. …Whether you use bricks... …Whether you use concrete blocks... b. Building this house will cost you a lot whether you use bricks or concrete blocks. 2. a. This machine will continue running.... whether you turn on this switch... …whether you turn off this switch... b. This machine will continue running whether you turn on this switch or turn off. 3. a. I have not yet decided. …whether I will go to the library… …whether I will go to the museum... b. I have not yet decided whether I will go to the library or museum 4.a. Electrical power can be generated by machines. …whether the machines are driven by the energy of moving water... ….whether the machines are driven by the energy of falling water... b. Electrical power can be generated by machines whether they are driven by energy of moving water or falling water. 5. a. You have to get in touch with him. ….whether you send him a post card…....whether you send him a letter... b. You have to get in touch with him whether you send him a post card or a letter. 6. a. The factory must receive the spare parts in time. …whether we send them by air…...whether we send them by land... b. The factory must receive the spare parts in time whether we send them by air or land. 7. a. The refinery must be supplied with power. …whether the power station is nearby......whether the power station is far away... b. The refinery must be supplied with power whether the power station is near by or far away. 8. a. The submarine will transmit messages to the base....whether it is under the water… …Whether it is on the water… b. The submarine will transmit messages to the base whether it is under the water or on the Water B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. We do not allow cold water to enter the boiler. (undesirable) b. It is undesirable to allow cold water to enter the boiler. 2. a. We should eliminate the current producing heat as far as possible. (desirable) b. It is desirable to eliminate the current producing heat as far as possible. 3. a. You must maintain a film of lubricant over the wire during manufacture. (necessary) b. It is necessary to maintain a film of lubricant over the wire during manufacture. 4. a. We have no problem in pumping out the water from the condenser. (not difficult) b. It is not difficult to pump out the water from the condenser. 5. a. You notice that the current generates heat in the core. (obvious) b. It is obvious that the current generates heat in the core. 6. a. You have to temper the metal after it has been quenched. (essential) b. It is essential to temper the metal after it has been quenched. 7. a. We normally connect the generator to a pair of feeding points. (usual) b. It is usual to connect the generator to a pair of feeding points. 8. a. You can reduce the amount of friction by using rolling bearings. (possible) b. It is possible to reduce the amount of friction by using rolling bearings. ((_9_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. When the steam is superheated, it is less likely liable to cause cylinder condensation. b. when super heated, the steam is less likely liable to cause cylinder condensation. Or b. The steam when superheated is less likely liable to cause cylinder condensation. 2. a. When copper is alloyed with tin, it forms a series of alloys known as bronze. b. When alloyed with tin the copper forms a series of alloys known as bronze. Or b. The copper when alloyed with tin forms a series of alloys known as bronze. 3. a. If zinc is rolled into sheets, it can be used for roof-covering, etc. b. if rolled in to sheets, zinc can be used for roof-covering, etc. Or b. Zinc if rolled in to sheets can be used for roof-covering, etc. 4. a. Once the combustible mixture is ignited, it expands rapidly. b. Once ignited, the combustible mixture expands rapidly. Or b. The combustible mixture once ignited expands rapidly. 5. a. If the engine runs at very high speed, it is liable to vibrate. b. If running at very high speed, the engine is liable to vibrate. Or b. The engine if running at very high speed is liable to vibrate. 6. a. When organic compounds are heated sufficiently, they burn away completely b. When heated sufficiently, organic compounds burn away completely. Or b. organic compounds when heated sufficiently burn away completely. 7. a. If the engine is lubricated properly, it works with high efficiency. b. If lubricated properly, the engine works with high efficiency. Or b. The engine if lubricated properly works with high efficiency. B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. If the water is hot, it will be pumped out of the condenser. b. If hot, the water will be pumped out of the condenser. Or b. The water if hot will be pumped out of the condenser. 2. a. If the frictional losses are very low, they can be ignored in the calculation. b. If very low the frictional losses can be ignored in the calculation. Or b. The frictional losses if very low can be ignored in the calculation. 3. a. When the highest thermal efficiency is necessary, it can be obtained from the Carnot cycle. b. When necessary, the highest thermal efficiency can be obtained from the Carnot cycle. Or b. The highest thermal efficiency when necessary can be obtained from the Carnot cycle. 4. a. If the particles in solution are present in liquid, they will carry the current through the liquid. b. If present in liquid, the particles in solution will carry the current through the liquid. Or b. The particles in solution if present in liquid will carry the current through the liquid. 5. a. If the temperature is not constant, it can change the result of the experiment. b. If not constant the temperature can change the result of the experiment. Or b. The temperature if not constant can change the result of the experiment. ((_10_)) A. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. The velocity of sound is considerably less than the velocity of light. b. The velocity of sound is considerably less than that of light. 2. a. The rate of expansion of a gas is greater than the rate of expansion of a liquid. b. The rate of expansion of a gas is greater than that of liquid. 3. a. The melting point of ice and the melting point of ice and salt are different. b. The melting point of ice and that of ice and salt are different. 4. a. The mechanism of an internal combustion engine is different from the mechanism of a jet engine. b. The mechanism of an internal combustion engine is different from that of a jet engine. 5. a. There are several systems of measuring temperature, but today the system of centigrade is used in science. b. There are several systems of measuring temperature, but today that of centigrade is used in science. 6. a. A thermometer used to measure room temperature differs from a thermometer used to measure body temperature. b. A thermometer used to measure room temperature differs from that of used for body temperature. B. Do the following exercises according to the explanations given in the Pre-Reading Part. 1. a. In plants, fibers are found in roots and stems. They are found in pulpy parts of leaves and stalks. b. In plants, fibers are found not only in roots and stems, but also in pulpy parts of leaves and stalks. 2. a. Rayon fibers are used by themselves. Rayon fibers are used with other fibers, both natural and man-made. b. Rayon fibers are used not only by themselves, but also with other fibers, both natural and man-made. 3. a. Bast fibers are used for making rope. They are used for making mats and sacks. b. Bast fibers are used not only for making rope but also for making mats and sacks. 4. a. Man uses natural fibers in textile industry. Man uses artificial fibers in textile industry. b. Man uses not only natural fibers in textile industry but also artificial fibers. 5. a. Most animal fibers consist of compounds of carbon, oxygen, hydrogen and nitrogen. They sometimes contain sulfur. b. Most animal fibers not only consist of compounds of carbon, oxygen, hydrogen and nitrogen but also they sometimes contain sulfur. Pigment: natural and man-made fibers_d Tentering: natural and man-made fibers_f Saturate: natural and man-made fibers_h Cohesion: natural and man-made fibers_l Shearing: natural and man-made fibers_k Sizing: natural and man-made fibers_i Combing: natural and man-made fibers_a Affinity: natural and man-made fibers_b Stratum:Concrete technology_g Verify:Concrete technology_j Contract:Concrete technology_i Damp:Concrete technology_f Grind:Concrete technology_l Plane:Concrete technology_b Ductility:Concrete technology_d  Bind:Concrete technology_a Elapse:Radar operation_f Spectrum:Radar operations_j Propagation:Radar operations_a Initiate:Radar operations_l Aerial:Radar operations_h Scan:Radar operations_c Synchronize:Radar operations_b Inoperative:Radar operations_g Transceiver: Microwave for communications_b Converge: Microwave for communications_h Velocity:Microwave for communications_n Ultra-short waves:Microwave for communications_l Communicating:Microwave for communications_o Loudspeaker:Microwave for communications_j Synchronize:Microwave for communications_e Wavelength:Microwave for communications_m Headset:Microwave for communications_a Amplify:Microwave for communications_k Bellows:iron and steel_h Firebrick:iron and steel_f Reverse:iron and steel_g Tuyeres:iron and steel_a Tarnish:iron and steel_b Fluid:iron and steel_e Geology:Civil engineering_h Transmissible:Civil engineering_i  Tension:Civil engineering_a Compact:Civil engineering_g Moisture:Civil engineering_b Support:Civil engineering_c Kerosene:oil_d Grease:oil_a Torch:oil_i Combustion:oil_e Pour:oil_h Fuel:oil_b Computer system:The electronic computer_l Hardware:The electronic computer_a Software:The electronic computer_j Data:The electronic computer_g  Memory:The electronic computer_c Console:The electronic computer_d Plant:The electronic computer_e Consist of:The electronic computer_f Electromagnetism: What is electricity_d Efficiency:What is electricity_a Magnetization:What is electricity_e Loop:What is electricity_j Electrify:What is electricity_f Generate:What is electricity_b Kinetic:What is electricity_h Transmit:What is energy_d Rotate:What is energy_h Define:What is energy_e Principle:What is energy_g Device:What is energy_a Huge:What is energy_c