Англ AC/DC

Задание 1. Найдите в правой колонке русские эквиваленты английских слов и      словосочетаний:

1.direct current    А) проводник
2. alternating current    Б) электрическая тяга
3.conductor    В) выпрямитель
4.electric traction    Г) менять
5.rectifier    Д) частотность
6. to change    Е) провод
7. fre¬quency    Ж) энергия, питать энергией
8.wire    З) использовать
9.power    И) переменный ток
10. to use    К) постоянный ток

Задание 2. Переведите на русский язык интернациональные слова:  
Principle, control, sys¬tem, cycle, sec¬ond, substation, volt, historical, metro, line, direction, transmission distribute diode

Задание 3.Прочтите текст и выполните следующие за ним упражнения:

AC AND DC DIFFERENCES

        To understand the principles of modern traction power control sys¬tems, we must know the difference between AC and DC circuitry. DC is direct current — it travels in one direction only along a conductor. AC is alternating current — so called because it changes the direction, flowing first one way along the conductor, then the other. It does this very rapid¬ly. The number of times it changes direction per second is called the fre¬quency and is measured in Hertz (Hz). It used to be called cycles per sec¬ond, in case you have read of this in historical papers.
      Fr om a transmission point of view, AC is better than DC because it can be distributed at high voltages over a small size conductor wire, whereas DC needs a large, heavy wire or, on some DC railways, an extra rail. DC also needs more frequent feeder substations than AC — the ratio for a railway averages at about 8 to 1.
     Over the years, since the introduction of electric traction on railways, the rule has generally been that AC is used for longer distances and on main lines and DC for shorter, suburban or metro lines. DC gets up to 3,000 volts, while AC uses 15,000 to 50,000 volts. Until recently, DC motors have been the preferred type for railways because their characteristics were just right for the job. They were easy to control, too. For this reason, even trains powered from AC supplies were usually equipped with DC motors.
Before passing AC to the motors, it has to be changed to DC by passing it through a rectifier. For the last 30 years, rectifiers have used diodes and their derivatives, such as: thyristors and choppers, the de¬velopment of which has led to the present AC traction systems.
Ответьте на вопросы согласно текста.

1. What is AC?
2. What is DC?
3. What is  fre¬quency?
4. What is better AC or  DC?
5. Wh ere is AC used?

Задание 4.Переведите на русский язык  3-й абзац текста в письменной форме.  

Задание 5. Закончите предложения, выбрав соответствующий вариант окончания:
1. DC (direct current) travels …
2. AC (alternating current) changes …
3.  DC motors have been …
4. For the last 30 years, rectifiers have used …
А) the direction, flowing first one way along the conductor, then the other.
Б) the preferred type for railways
В) diodes and their derivatives.
Г) in one direction only along a conductor.

Задание 6. Назовите номера предложений, в которых имеются причастие 1, причастие 2 и переведите их на русский язык:
1. Being a large cultural centre Moscow attracts a lot of tourists.
2. The  Kremlin standing on the bank of the Moscow river is the oldest part of Moscow.
3. Washington named after the first American President is situated on the Potomac River.
4. Moscow founded by Yuri Dolgoruky is one of the oldest Russian cities.
5. Millions of emigrants cross the ocean hoping to find a better life  in the USA.

Задание 7. Назовите номер предложения, эквивалентного данному русскому предложению:
Я никогда не был в Лондоне.
1. I didn’t go to London last year.
2. I have never been to London.
3. I wasn’t in London when it happened.

Задание 8. Назовите номера предложений глагол, которых стоит в Continuous Tense (продолженное время), и переведите их на русский язык:
1. They are visiting the Tretyakov Gallery now.
2. The workers were building a new bridge when we saw them.
3. Feeling not well she decided not to go to the party.
4. They will be visiting the Tretyakov Gallery between 2 and 3 o clock.

Задание 9. Заполните пропуски модальными глаголами (must, can, may)
1. He (   ) check a fuel level in his car.
2. You (  )  easily do this work.
3. You (  ) find all necessary material in the library.
4. He (  ) check the temperature three times a day.
5. You (  )  use this method in your work.