1.

10. Compressing a gas quickly raises its temperature. 11. This machine needs repairing. 12. This book is worth reading. V、

Let us begin our study of electricity by examining the results of a few basic experiments. The first experiment consists of stroking a rubber rod with some fur, and then in turn touching two small pith balls suspended from strings with the rod. The pith balls then swing apart, indicating that a repulsive force now acts between them. Next, we stroke a glass rod with a silk cloth and touch two different suspended pith balls in turn with it. Once more the pith balls swing apart, indicating a repulsive force. Now we bring near each other one of the pith balls touched with the rubber rod and one touched with the glass rod; they swing toward each other this time, indicating an attractive force. VI、

1. The results obtained indicate that these two methods are consistent in essence, with the exception that they have their own specific application conditions.

2. A new algorithm has been designed which will be able to maintain the survival of useful copies, thus greatly reducing the number of packet copies in a network.

3. Given [Knowing] resistance and current, one [we] can determine voltage.

4. The price of this instrument is high.

5. This device occupies too much space/room. 6. A robot is a special kind of electronic device.

7. This scientist said, “Electrons move round the nucleus.”

8. The current starts flowing at the very moment we close the circuit. 9. There are a few exceptions to this rule.

10. They have been designing a new type of computer these six months.

练习

9

II、

1. The problem was not to be solved until a completely new method was

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introduced.

2. The values of most things must be converted from decimal to binary before computations can begin. 3. A body at rest will never move until force compels it. 4. Nearly 100 years passed before the existence [presence] of subatomic particles was confirmed by experiment [experimentally].

5. Diode D conducts the moment [the instant; directly; immediately] the input voltage becomes more negative than V.

6. The first time they designed an electronic computer, scientists encountered many difficulties.

7. The year this device was invented, World War II broke out. 8. Small as they are, atoms are made up of still smaller particles. 9. The voltage is always there while the generator is operating. 10. As current flows, part of its energy will be lost. 11. These two resistors should be selected [chosen] so that the transistor can operate normally.

12. The body is in such a state that it can do work. III、

1. The relation that voltage is the product of current and resistance applies to all the dc circuits.

2. The fact that everything around us is matter is known to all. 3. The discovery that magnetism can produce current is extremely important in the field of electricity.

4. There is no doubt that the magnetic field is produced by some sort of circulating current. 5. An equation is an algebraic statement that two algebraic expressions are equal. 6. There is evidence that the mass of a body is the function of the body. 7. The question now arises whether this result applies to all cases. 8. In this case there is no guarantee that the series is convergent. 9. There is a growing awareness that these techniques are very useful. 10. One of [Among] the most noteworthy achievements at that time was the realization that light consists of electromagnetic waves. 11. The advent of electronics is reckoned from the discovery that the current in the vacuum diode can be controlled by introducing a third electrode. 12. This is due to [ is caused by; results from] the fact that there are many free electrons in conductors. 17 / 43

13. There is no evidence that energy can be created or destroyed. 14. This series of experiment leads to the result that with a constant applied [external] force, the acceleration is inversely proportional to the mass. 15. Besides [In addition to] the fact that the properties of the material should be included in the analytical model, we must take other factors into account. IV、

Nearly all substances fall into two major [broad; general; main] categories: conductors and insulators. Metals, many liquids, and plasmas are conductors, while nonmetallic solids, certain liquids, and gases are insulators. Just as the rate of flow of water depends upon the difference of height between them, the rate of flow of electric current between two points depends upon the difference of potential between them. The statement that voltage is proportional to current multiplied by [times] resistance is called Ohm’s law, since it was first verified experimentally by the German physicist Georg Ohm. V、

1. Compared with the theory presented in the literature published abroad in recent years that the polar axis should be in parallel with the earth’s axis, the method given in this paper will lead to (a) higher accuracy.

2. These features make it difficult for electronic counter-measure systems to intercept, analyze and jam this kind of signals.

3. By the family of curves is meant a specified set of curves which satisfy given conditions.

4. The existence of and the ability to control these phenomena make those devices possible.

5. In this case it is necessary to use as much energy of signals as possible. 6. The variation of the number of the filter’s teeth has a greater effect on the performance of its passband than the variation of its dimensions.

7. Scalar detection will result in the loss of some phase information.

8. Fig. 6 shows the schematic diagram of measuring scatter parameters by the natural parameter transformation method.

练习 II、

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10

1. Now it remains to be determined when the series converges. 2. It is clear from Dubamel’s Theorem that this limit exists. 3. How large this error is depends upon several [a few] factors. 4. It is a matter of indifference which point of view is adopted. 5. It should be emphasized that these definitions may be used for angles of any magnitude. 6. It is assumed that the student has a basic understanding of mechanical drawing. 7. It follows from Maxwell’s hypothesis that whenever there is a change in an electric field, a magnetic field is produced. 8. It happens that the overall phase shift is zero. 9. It does not matter whether the magnet is moved in this case. 10. It makes no difference which unknown is selected [chosen]. 11. Temperature determines in what direction the transfer of heat will take place. 12. Which equation we should use depends on what data we are given [know] in the problem. 13. It is now a well-known fact that all matter consists of tiny particles. 14. It has been found that the direction of an electric current is opposite to that of the flow of electrons. III、

1. It is necessary to determine under what conditions this equation holds [applies; is valid; is true]. 2. This device is just what we need. 3. Now we summarize what we have proved so far [up to now]. 4. What a generator does is to change mechanical energy into electrical energy.

5. What this chapter describes [What is described in this chapter] is of great importance.

6. This magnetic force is what makes the electric motor run. 7. Matter is what can occupy space. 8. This is what happens in a transistor. 9. What we have discovered in this experiment is the entirely new realm of electrical phenomenon.

10. This direction is opposite to what has been assumed.

11. What is spoken of as absolute zero is the temperature 273oC below zero. 12. Television and telephone communications are linking people to a global

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village, or what one writer calls the electronic city. 13. Magnitude, direction, and place of application are what we call the three elements of a force. 14. These numbers constitute what is known as the real number system. 15. After a chemical change, a substance is changed to something different from what it was. 16. In what follows, we acquaint ourselves with some basic concepts. IV、

It is said that Galileo found, after a number of experiments, that all bodies near the earth fall toward the earth with the same acceleration. This acceleration is what we call the acceleration of gravity. Galileo’s work was especially significant because, for the first time, experimental results were accepted despite the fact that they contradicted well-known established ideas, in this case the notion that heavy things “should” fall faster than light ones. What deserves to be commented on Galileo’s work is that his conclusion that all things fall with the same constant acceleration is only an idealization of reality. V、

1. An x-band wave-guide test system is shown in Fig.7. [或：Fig. 7 shows …].

2. This method lowers the requirement for the hardware of a sample network.

3. On the basis of the above analysis of the decomposition of the polynomial, a novel configuration results. [或：The above analysis of the decomposition of the polynomial results in a novel configuration.]

4. This can satisfy the system’s input and output rates with as low a systolic frequency as possible.

5. This paper discusses the design guideline for and the structure of the system, with a deep inquiry into model testing.

6. Finally, an analysis of packet loss probability is made by computer simulation.

7. The sparse ratio of the resulting impedance matrix is as high as 40%. 8. The Qin Yong-brand whole milk powder is made from high-quality fresh milk, white sugar and trace elements needed by the human body by scientific methods and Denmark’s advanced technology.

The Qin Yong-brand whole milk powder contains calcium, protein and varied vitamins, and it can be mixed with lukewarm sanitary drinking water into [或：… can be blended with lukewarm sanitary drinking water to produce]

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