Language activity

Exercise 1. Complete the following sentences with a, an, the or no article.

1. … audience clapped and cheered.

2. People say … British are not very friendly but I disagree.

3. If we do not protect … nature, our environment will get worse and worse.

4. I pick up … kids from school and take them … home when Mary is at … work.

5. Take these letters to … post office, will you?

6. Are we going round to … Wilson’s for supper on Saturday?

7. Where do you work during … day?

8. What will you do if they cut … electricity off?

9. The Government should tax … rich more and … poor less.

10. … power doesn’t interest him but … money does.

11. We arrived at Heathrow and got … taxi which took us to … Oxford Street.

Exercise 2. Insert prepositions where it is necessary.

1. The first lens was a liquid lens, formed … a droplet of water.

2. Convex lenses are thicker … the center.

3. A lens that consists … one element is a simple lens.

4. Nonplanar surfaces of a lens are often spherical segments and are coated … thin dielectric films.

5. Lenses are made … a wide range of forms.

6. Photography depends … a photochemical reaction in an emulsion of silver halide crystals.

7. An optical image is the reproduction … an object … a lens or mirror system, employing light as a carrier.

8. It is impossible to get any kind of image … light.

Exercise 3. Summarize your knowledge of Present Perfect Tense. Put the verbs in brackets into the correct form.

1. The students (to read) the articles today.

2. He never (to conduct) such experiments.

3. The manufacturing technology (to improve) to the point that more complicated computers can be produced.

4. The production of lenses already (to become) an important branch of optical industry.

5. “You ever (to be) to such a conference?” professor asked the post – graduate student.

6. He not (to come) home yet.

7. The astronomer just (to write) down all the observations of the planets.

8. Two foremost opticians (to complete) a great scientific work this year.

Exercise 4. Summarize your knowledge of Past Perfect and Future Perfect Tenses. Translate the sentences from Russian into English.

1. Они прочитали, перевели и записали текст к тому моменту (до того), как он пришёл.

2. Инженеры закончат испытывать самолёт к 3 часам.

3. Конференция закончится к полудню.

4. Студентка уже сдала экзамен к 5 часам.

5. Учёные закончат работу к концу месяца.

6. Уже к 1610 году Галилей сообщил о проведении первых телескопических наблюдений.

7. К 2005 году будут созданы ещё более мощные телескопы.