Put questions to the words in bold type.

1. The students made two experiments: they were both interesting and useful. 2. Both scientists studied atmospheric electricity. 3. Both of us will work in the Institute laboratory tomorrow. 4. Both Lomonosov and Rihman were great scien­tists; both of them worked at atmospheric electricity. 5. Both these devices were constructed in Moscow. 6. Electricity is used both in industry and in everyday life. 7. Both nuclear power and solar power will be widely used in the future. 8. Lightning and atmospheric electricity are one and the same thing: both of them are used in literature. 9. Many scientists and inventors, both Russian and foreign, have greatly contributed to the development and practical appli­cation of the electric current. 10. Both chemical power and mechanical power can be changed into electricity.

9. Fill in the blanks with prepositions:

1. It is dangerous to go ... a stormy day. 2. Lightning is a very great flash ... light resulting ... a discharge ... atmos­pheric electricity. 3. Protecting building ... lightning was the first discovery ... thefield ... electricity used ... the good ... mankind. 4. ... thousands ... years people knew noth­ing ... thunderstorms. 5. Lightning flashes are followed ... thunder which can be heard ... kilometres around. 6. There is always some danger ... a thunderstorm ... a very high build­ing or a man standing .. the open field. 7. It is difficult to see a single drop ... water ... the sea. 8. Some scientists ..the past melted metals ... the help ... solar furnaces. 9. Mo­dern civilization cannot do ... electrical appliances. 10. The electric current is necessary ... the operation ... trolley­buses, buses and modern trains.

10. Translate into Russian:

(a) the only son; the only example known; the only method of solving the problem; only you can do it for me; coal is not only a source of heat, but also a source of valuable chem­ical substances; the letter was sent only yesterday;

(b) many students were present; at the present time; the present article; he is in Moscow at present; that is all for the present; good-bye for the present.

11. Form five sentences combining suitable parts of the sentence given in Columns I and II:

I II

1.Generator 1. measures the temperature of hot melted metals.

2.Lightning conductor 2. lifts objects weighing thousands of tons.

3.Battery 3. turns electrical power into mechanical

power.

4.Electric crane 4. protects buildings from lightning strokes.

5.Pyrometer 5. turns mechanical power into electrical power.