Telegraphy.

Electricity completely changed communications. Once it was discovered that electric current flows along a wire, it seemed possible that it could be used for messages. As long as two places were connected by a wire electric impulses could be sent along it. It meant that people were able to send messages a long way at great speed. The new way of communication had a lot of advantages and by the end of the 19^th century cables were laid all over the world.

Samuel Morse, one of the most famous people in communications, invented a special code, which we call now "the Morse code". He thought of using short and long electric impulses. Combining different sets of impulses he made a code for the whole alphabet, and the numbers from 0 to 9. This code was the easiest and the fastest to transmit.

Later on the necessity aroused to increase the speed of sending messages. People decided to use the fact that current could flow one way round the circuit or the other. A new system called double current working" was worked out According to this system a dash and a dot are impulses of the same length but of different directions.

Then a machine was invented to send typewriter messages over a telegraph circuit. Such machines are called teleprinters or teletypes and use International 5-unit code instead of the Morse code. Each letter or figure is made up of five impulses of electric current, either positive or negative, all letters being the same length in time. A teleprinter has a keyboard and every- time one of the keys on the keyboard is pressed it sends the five impulses that make one letter or figure.

As most modern systems use alternating current, one line can be used to send many messages at the same time. It is possible if each message is sent out at a different frequency. This allows high-speed telegraph communication as well as transmission of written messages.

Вариант 9.

Задание 1. Измените число существительных с единственного на множественное и внесите соответствующие изменения в остальные члены предложений.

1. A fox often prowled about the farm yard, seeking a fat goose to carry off.

2. As soon as the train has arrived, the postman will deliver the letter.

3. A passer-by saw the accident.

4. The leaf turned first yellow and then brown, and dropped off and was blown into the corner of the garden.

5. The valley is green, and a deer is grazing in it.

6. The ox has hurt its hoof, and cannot draw the cart.

Задание 2. Измените форму прилагательных, данных в скобках, и переведите предложения на русский язык.

1. Susan is (old) than Mark; she is the (old) of the family.

2. The weather is (dull) today than it was yesterday.

3. London is (big) than Manchester. Manchester is (small) than London.

4. Jack is (rich) than Richard, but I don't think he is (happy) than Richard.

5. My dog is as (good) as yours.

6. What (nice) present is there than a box of chocolates?

Задание 3. Вставьте модальные глаголы may, can, must, need.

1. There are no buses or taxis, so we... walk.

2. We ... go away just yet; our train doesn't leave for half an hour yet.

3. The ice is quite thick. We ... walk on it.

4. ... I use your phone? — You... ask for permission, you... use it whenever you like.

5. She ... sing quite well.

6. We ... live without food and water. We ... eat and drink.

Задание 4. Поставьте глаголы, данные в скобках, в нужную форму.

1. I (tell) you the answer yesterday.

2. John and Richard just (go) away.

3. The clock is slow. - It isn't slow, it (stop).

4. He (not smoke) for two weeks. He is trying to give it up.

5. I (fly) over Loch Ness last week. - You (see) the Loch Ness monster?

6. I can't go out because I (not finish) my work.

Задание 5. Переведите предложения на английский язык.

1. Мой брат никогда не носит шляпу лету.

2. Боюсь, я проиграл эту партию в шахматы (this game of chess). Я играл очень плохо. Обычно я играю намного лучше.

3. Я не играл в футбол с 1983 года.

4. Он писал письмо, когда я увидел его.

5. Как только я начал интересоваться своей работой, мне нужно было идти домой.

6. Петр обычно делает домашнее задание перед ужином.

Задание 6. Образуйте отрицательную и вопросительную формы предложений.

1. They will have done this work by 11 o'clock tomorrow.

2. I was repairing my car the whole day yesterday.

3. My friend knows Spanish very well.

4. I'll be translating this text the whole morning tomorrow.

5. Yesterday I came home at 6 o'clock.

Задание 7. Задайте вопросы к каждому члену предложения.

1. He will be working at the library at this time tomorrow.

2. My friends often invite me to the parties.

3. She is working in the library now.

4. We discussed this problem last week.

5. The news will be of great interest.

Задание 8. Задайте общий, специальный, альтернативный и разделительный вопросы к каждому предложению.

1. I was repairing my car the whole day yesterday.

2. My friend knows Spanish very well.

3. Yesterday I came home at 3 o'clock.

4. The cat is sleeping before the fire.

5. There were three mistakes in my test.

Задание 9. Переведите текст на русский язык.