Learn the following active words and use them in the sentences of your own.

assume считать, полагать

blade лопасть

boiler бойлер, паровой котел

consumption потребление

installation установка

irreplaceable незаменимый

radia­tion излучение

receive получать

sunbeam солнечный луч

space, spaceship космос, космический корабль

store хранить

thermal термальный, тепловой

Put questions to Fig. 18.

Speak on possible uses of solar power.

Compose a story looking at Fig. 18.

5. Answer the following questions:

1. There is black coal—the coal from the mines. Where is it used?

2. There is "white coal"—the power of the waterfall. Where is it used?

3. There is "sky blue coal" — the power of the wind. Where is it used?

4. There is "blue coal"—the power of the tides of the sea Where is it used?

5. There is "yellow coal"—the power of the sun. Where is it used?

6. Read and retell the following story:

The Sun and the Moon

Two men were arguing one day about the sun and the moon, and which of the two was more useful. At last one them said, "Oh! I know. The moon is quite worth two sun for it shines at night when it is needed, but the sun shines: the daytime when nobody wants it."

ADDITIONAL GRAMMAR EXERCISES

The Participle

1. This brief description of some of the methods used in our work covers only a few of the problems encountered. 2. The resistance being very high, the current in the circuit was low. 3. As useful as lasers are becoming, we have hardly yet begun to realize their ultimate potentialities. 4. The test referred to above can be easily made. 5. There is always water vapour in the air, the amount depending upon various conditions. 6. Until now we have been discussing reactors from which no power is being taken. 7. The region of highest resistance is the point of contact between the pieces being welded. 8. Some of the effects produced by an electric current are discussed in the following chapter. 9. The voltage being increased, the field becomes strong enough to cause the electrons to produce addi­tional ions by collision. 10. The filament heated, the electrons leave its surface and travel to the plate. 11. Multiplying the mass of a moving body by its velocity, we shall- get its momentum. 12. These suggestions are based on practical experience gained in the design of a considerable number of laboratories not to speak of the discussions with experienced workers in the field of thermodynamics. 13. In many instances an apparatus designed for quite a different purpose was adopted, certain changes being made when required. 14. The problem having excited a great deal of discussion, a series of tests had to be carried out. 15. The oil having been exhausted, the engine stopped. 16. There are two diagrams in this figure, one of them showing the relation between volume and temperature. 17. Working at his new device, the inventor made numerous improvements, the latter resulting from his own experi­ments.

The Gerund

1. They went on studying the nature of that new phenom­enon. 2. There are different means of producing an electrical current. 3. We heard of that experiment having been started last week. 4. Radioisotopes may be used in measuring the diffusion of metals. 5. Before discussing the future development in isotope utilization, let us trace briefly the events leading to its discovery. 6. This motor is capable of effectively operat­ing completely submerged in water as a thin-shelled can completely protects the stator. 7. An unusual electric motor has been developed which creates linear motion directly without going through rotating motion first. 8. In addition to its being used as a wide-range voltmeter, the instrument can serve as an ammeter. 9. Comparing the performance of these instruments is the only means of solving the problem under discussion. 10. The trouble was due to the fact that the engine was put into operation instead of having been tested first. 11. Laboratory testing will expand rapidly at our Institute. 12. The value of the accelerating torque determines the time taken by the motor to reach full speed from the moment of switching on. 13. Some types of motor are not suit­able for braking duty, and the requirement must be specified at the time of ordering. 14. One cannot appreciate the marked improvement achieved without comparing tables 2 and 3.15. The machine broke on account of its having been made of a delicate material. 16. We have learned of his starting a series of new laboratory experiments. 17. Normally, stainless steels referred to above are welded without preheating and postheating.

The Infinitive

1. It is necessary that the sample to be analysed be chemi­cally pure. 2. The following precautions should be observed to insure valid results in our experiment. 3. To find an instru­ment better suited for our testing was the next problem to be solved. 4. We know the strength of a current to depend upon the resistance of the circuit. 5. For a long time the atom was thought to be indivisible. 6. A three-inch tube has been found to be satisfactory but it is entirely practicable to use

greater tubes if needed. 7. The oscillograph to be used for testing purposes is similar to that used in our laboratory. 8. If considered from this point of view, the problem seems to be rather complicated. 9. Radium is said to be one and a half million times more radioactive than uranium. 10. Tests have shown the thermometer to be very sensitive. 11. The oscillator referred to above seems to deliver only a small amount of pow­er. 12. The instrument to be described here was developed several years ago. 13. To analyze this effect is to take into consideration all the elements of the circuit. 14. To analyze this effect we shall consider all the elements of the circuit. 15. We expected the discovery to have produced great changes. 16. It is necessary to explain why the formulas given here are correct. 17. To explain that the formulas given here are correct, it is necessary to study them first. 18. To explain why the formulas given here are correct would require considerable space. 19. The apparatus to be designed is to be used at the power station. 20. This type of engine is said to have many disadvantages. 21. The effect of connecting cells in series is to increase the total voltage. 22. To find out the state of a mass of a gas is quite possible. 23. To find out the state of a mass of a gas one should know its volume, its pressure and its tem­perature. 24. The ammeter is the very instrument to measure the electric current. 25. A piece of apparatus which has the ability to maintain one of its terminals at a higher potential than the other, even though the current is allowed to flow through it, is said to develop an electromotive force. 26. To heat a body we place it in contact with another body at a higher temperature. 27. We expect most bodies to expand when heated. 28. To achieve good results we are expected to proceed in the following manner. 29. Under such conditions laboratory testing is assumed to continue to expand rapidly. 30. Todrive machines requires power.