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Text C

INSULATORS

Insulating materials have a very low conductivity. They offer extremely high resistance to the flow of current. Insulators are used in electric devices to isolate conductors. Thus they should have a high dielectric strength and a high resistivity. Their mechanical properties are also important for practical use.

Insulators are divided into gaseous, liquid and solid. They are also divided into groups according to their heat resistance.

The main gaseous insulator is air. At 20°C the dielectric strength of air is extremely low; it is lower than the strength of most liquid and solid dielectrics.

Liquid insulators are mineral oils, synthetic liquids, resins, and others. Of them mineral oils are used in oil transformers, cables and capacitors. In transformers, oil is used to insulate current conducting parts. Thus, it should have a high dielectric strength (10 to 20 mV/m). As to resins, at low temperatures they are amorphous. When heated, they become first plastic, then liquid. Resins are the most important components of many plastics. (Commonly used in electrical engineering are synthetic (polymeric) resins — polyethylene). Plastics are used as wire and cable insulation. Solid insulators are paper, cloth, plastics, and porcelain. Of them plastics are widely used in electrical engineering as insulating and structural materials. As to porcelain, it is highly resistant to mechanical factors and heat. Due to this property it is used to produce low- and high-voltage insulators.

Времена группы Simple

В случае если нужно сообщить о действии или состоянии в настоящем, прошедшем или будущем, не указывая на характер протекания действия, то употребляют Present, Past, Future Simple в зависимости от времени действия. Для образования вопросительной и отрицательной форм используются вспомогательные глаголы do (does) – Present Simple, did – Past Simple, shall / will – Future Simple.

Eсли сказуемое выражено глаголом to be, to have или модальными глаголами (can, may, must и др.), то отрицательная и вопросительная формы образуются ими самостоятельно, без помощи вспомогательных глаголов.

Спряжение глаголов группы Simple

         
Present Simple Past Simple Future Simple
  2 3
Утверди-тельная I ask, make He (she) asks, makes We (you, they) ask, make I asked, made He (she) asked, made We (you, they) asked, made I (we) shall ask, make He (she) will ask, make You (they) will ask, make
  2 3
Вопроси-тельная Do you ask? make? Does she ask? make? Did you (they, we, he) ask? make? Shall we ask? make? Will he (you, they) ask? make?
Отрица-тельная I do not (don’t) ask, make He (she) does not (doesn’t) ask, make I (he, she, they) did not (didn’t) ask, make I (we) shall not (shan’t) ask, make He (she, you, they) will not (won’t) ask, make

Глагол to be

(to be – was / were – been)

Синтаксическая функция и значение Пример и перевод
1. Смысловой глагол со значением «быть», «находиться» (когда за ним следует существительное с предлогом или наречие) The new device is in the laboratory. Новый прибор находится в лаборатории.
2. Глагол-связка (в сочетании с предикативом) со значением «быть», «являться», «состоять», «заключаться» My father is a designer. Мой отец – конструктор. Our aim is to obtain reliable results. Наша цель состоит в том, чтобы получить надежные результаты.  
3. Вспомогательный глагол для образования форм: a) Continuous, Perfect Continuous   b) страдательного залога     She was listeningto the radio in the kitchen. – Она слушала радио на кухне. It has been raining since 9 o’clook a.m. – Дождь идет с 9 часов утра. The telephone was invented by A.Bell. Телœефон был изобретен А.Беллом.
4. Модальный глагол со значением «должен», когда он стоит перед инфинитивом смыслового глагола с частицей “to” The lecture is to begin at 10 o’clock. Лекция должна начаться в 10 часов.

I.Choose the correct phrase underlined in each sentence.

1. What time go you/do you go to bed on Saturdays ?

2. Why are you waiting/do you waiting outside the door?

3. Don’t ask Tim. He doesn’t know/not knows the answer.

4. I having/I’m having my lunch at the moment.

5. When you leave/do you leave the house ?

6. I don’t understand. What is happening/is happen?

7. Excuse me, does you know/do you know the time?

8. This is a great party. I’m having/Am I having a lovely time.

9. We can’t use the lift because it don’t works/doesn’t work.

10.What you are doing/are you doing here?

II. Read the answers and then complete the questions.

1. Where ..does Sue…….live………………….?

Sue? She lives at the end of Axwell Road.

2. Do ……………………………………………….?

Jim? No, I don’t know him.

3. What………………………………………...?

At the moment? I'm doing my homework.

4. Are………………………………………………...?

Here? No, I'm sitting over there.

5. Do………………………………………………….?

Here? No, we change trains at the next station.

6. Why……………………………………………………?

I'm wearing two pullovers because I feel cold!

7. Is…………………………………………………………?

David? No, he's not staying with Tom.

8. When………………………………………………….?

Kate? She comes home at 6.30.

III. Rewrite each sentence so that the verb underlined is a negative contraction.

1. Naomi and Bill are watching television.

Naomi and Bill aren’t watching television.

2. Pater likes chocolate cake.

……………………………………………………

3. Carol drives a little red sports car.

……………………………………………………

4. I'm using this pencil at the moment.

……………………………………………………

5. The children are having lunch in the kitchen.

……………………………………………………

6. The sun sets in the east.

……………………………………………………

7. I get up early on Saturday.

……………………………………………………

8. Kate is writing a novel.

……………………………………………………

9. Sue lives in London.

……………………………………………………

10. We’re waiting for you.

……………………………………………………

IV. Choose the correct sentence in each context.

a) You want to invite a friend to your party on Friday. You say:

1. I have a party on Friday. Do you want to come?

2. I'm having a party on Friday. Do you want to come?

b) You find a wallet on your desk and ask the people nearby:

1. Who does this wallet belong to?

2. Who is this wallet belonging to?

c) A friend invites you to a snack bar at lunch time. You say:

1.Thanks, but I always go home.

2. Thanks, but I'm always going home.

d) A friend opens the door and says: What are you doing? You reply: 1. I work as a secretary.

2. I'm repairing the computer.

e) A friend asks: Do you like lemon tea? You reply:

1. I prefer tea with milk.

2. I'm preferring tea with milk.

f) You haven't decided yet about buying a new bike. You say:

1. I think about it.

2. I'm thinking about it.

g) A friend asks you if you have finished the book she lent you. You say:

1. Sorry, I still read it.

2. Sorry, I'm still reading it.

h) It is a hot day, but a friend has a heavy coat on. You ask:

1. Why are you wearing a heavy coat?

2. Why do you wear a heavy coat?

V. Choose the correct word or phrase underlined in each sentence.

1. That can't be right!(I don't believe / I’m not believing it!

2. Carol can't swim today. She has/is having a cold.

3. See you in the morning. I leave/I'm leaving now.

4. What do you do/are you doing? If you drop it, it will explode!

5. Stop doing that, Billy! You are /You are being very silly.

6. I drive/I'm driving! You can sit in the back with Martin.

7. What do we eat/are we eating this evening? I'm really hungry! 8. You're a great cook! This cake tastes/is tasting wonderful.

9. Where do you go/are you going? I haven't finished speaking to you!

10. Chemistry is hard. I am not understanding/I don't understand it.

VI. Put each verb given into present simple or present continuous.

1. Ugh, don't show me that picture! I (hate) .../……hate……. spiders!

2. Who (you, go with)................ to the match on Saturday?

3. In the winter, what (you, wear)…………………..?

4. I can't stand horror films. I (think)………….they're really silly!

5. Diana (not, usually, sit)............. …………next to Ellen.

6. Why (you, look at)................ me like that? Have I done something

wrong?

7. Excuse me, but (this bus, stop)........ outside the Post Office?

8. I(not take).................... the bus to school today. My mother (give) …

…………. me a lift.

9. Don't worry about the cat. It (only eat)………….once a day.

10. I can't work out the answer, (you, know) what it is?

11. What's the matter? Why (you, stare) at me like that?

12. Excuse me, but (you, speak) … English? I'm looking for a hotel.

13. Helen (stay) ................. with her brother while her house is being repaired.

14. You should go on a diet. (you, put) ………………….on weight.

15. (they, speak) ………………. French or German? I can’t tell the difference.

VII. Choose the correct sentence, 1 or 2, in each mini-dialogue.

a) A: Can you come dancing tomorrow night? B: 1) Sorry, I'll play basketball.

2) Sorry, I’m playing basketball.

b) A: What are your plans for the summer? B: 1) I'll spend a month in the mountains.

2) I'm going to spend a month in the mountains.

c) A: What do you think about the weather? B: 1) It'll probably rain tomorrow.

2) It's raining tomorrow.

d) A: What about tomorrow at about 5.30.? B: 1) OK, I'll see you then.

2) OK, I'm seeing you then.

e) A: Mary is buying a dog next week.

B: 1) Really? What is she going to call it? 2) Really ? What is she calling it ?

f) A: It would be nice to see you next week.

B: 1) Are you doing anything on Wednesday ?

2) Will you do anything on Wednesday?

VIII. Put the verb given into a form of will, going to or present continuous. More than one answer may be possible.

1. Have you heard the news? Harry (join) …us.

2. Sorry to keep you waiting. I (not be)......... ……….long.

3. According to the weather forecast, it (snow) tomorrow.

4. I'm sorry I can't meet you tonight. I (go out) with my parents.

5. Careful! You (knock)................ that jug off the table!

6. In fifty years' time, most people (probably ride) ….bicycles to work.

7. Our teacher (give)............... us a test tomorrow.

8. I (go)..................... to Manchester at the end of next week.

9. Look out! You (hit). .................... that tree!

10. I think our team (probably win)………………………………. .

IX. Analyze the functions of the verb to be. Translate the sentences into Russian:

1. The results of the experiment are of great importance for our further work.

2. There are no chemical plants in our town.

3. The substance that we are speaking about is water.

4. We are to translate technical literature in the second year.

5. Technical progress is impossible without high quality materials.

6. Electronics is being used more and more throughout the industry.

7. The electron is a particle.

8. Our task is to finish the test by 7 o’clock.

9. Smoking is dangerous.

10. This scientific discovery was the result of six years research.

11. Our aim is to accomplish this task as soon as possible.

12. Their house is in the middle of the village.


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