Составить резюме по тексту: the pstn (the public switched telephone networks) we have been describing has a star configuration. local loops (usually one per subscriber) terminate in a co (central-office). this co completes connections from one local loop to another local loop or from one local loop to a trunk that terminates on some other co. this co has gone through a number of fundamental technological changes. the manual system required, of course, constant attention from operators. in the late 1800s, telephone calls were connected manually at the co. when a call came in, an attendant would plug into a horizontal bar line. he then would yell to the operator who handled the customer being called, and that second operator would connect to the bar and finish setting up the call. when the call was completed, another operator would yell to all in the room that the line was clear again. the step – by – step system, which is still in operation in many parts of country, utilized that is known as the stronger switch. the intelligence in the system was located in relays mounted on each switch. the switch itself responded to the dial pulses of the rotary dial. the crossbar system was still electromechanical in nature, but the intelligence of the system was separated from the actual switch. thus, this common control could be used repeatedly to set up and tear down calls and never sit idle. when electronics came along, the electromechanical control of the common control system was replaced with electronics, and the network, or matrix, was usually replaced with tiny glass – encapsulated reed switches. hence, only a part of the switch was electronic. in the next generation, the stored program operation of a digital computer was applied to the switch, the talking path was no longer an electrically continuous circuit; rather the speech being carried was digitized into a stream of “1s” and “0s.” notice that this final generation depicted a significant change from the previous generations in that there was no longer an electrical talking path through the switch. we were, in fact, operating in a digital (rather than analog) domain. however, whether the system was analog or digital, one thing must be recognized: there was an actual talking path – a circuit – from the calling party to the calling party. this talking path was established at the beginning of a call. we call it circuit switching. this system is not actually efficient. when i am talking, you are listening, and the circuit is being used in only one direction – that is 50 percent. when you are talking and i am listening, it is still 50 percent. when neither of us is talking, or when there is silence between words, the efficiency is 0 percent. there is, however, a different kind of connection, and we see it today in a number of applications: - credit-card verification; - automated teller machine; - ss7; - internet and the world wide web. this system is called packet switching(as opposed to circuit switching). in a packet-switching system, the information being transmitted (be it data or digitized voice) is not sent in real time over a dedicated circuit; rather it is stored in a nearby computer seizes a channel heading in the general direction of the destination, and that packet of data is transmitted at very high speeds. then the channel is released. so, except for some necessary supervisory information (destination, error checking codes, etc.) the channel is 100 percent efficient. when the distant station gets that message no more than a few milliseconds later, it responds with the necessary handshaking information - again, by accumulating a packet of data, seizing a channel, and bursting the information out over that channel. again, 100 percent efficient. as mentioned earlier, the packet networks in the world (actually overlay networks to the pstn) are being used extensively for data: only recently are we seeing them being used for voice. as systems are perfected, this also will change.
2. The boys exciting adventure stories in a week.
b. will read
3. I a very interesting detective story since yesterday.
a. Have been reading
4. Tom the second part of the story before we found it.
b. Had translated
5. Who the ink?
a. invented
6. We to tapes when you brought your book.
c. Were listening
7. My father is busy now. He his favourite TV show.
d. Is watching
8. The Lord Chancellor over the House of Lords.
a. presides
9. Who is looking your children when you are abroad?
c. after
10. This Princess turned everybody . Because she didn’t like anybody.
c. down
11. It’s getting . I must put on my coat.
c. cold
12. This is the family ring was lost a long time ago.
c. which
13. My parents never forgot the place they met.
b. where
14. ___ ___is very big country. ___ ___ are very friendly.
d. Russia, the Russians
15. “There isn’t in my tea.” – “sugar is not so good for your health.”
c. Enough sugar, -
16. If I learn this rule, I our English text.
c. will pass
17. Sarah to find friends in Spain if she progress in Spanish.
c. will be able, makes
18. You stop for me. I’ll come back later.
d. Don’t have to
19. Your elder brother go to school because he is ill.
a. Mustn’t
20. Neither your sister nor your brother like your father.
b. looks
21. This information isn’t . You should check it with other recourses.
b. reliable
22. write about private life of celebrities, gossip and .
c. tabloids
23. is one of the most popular British broadsheets.
a. The Sun (не уверена)
24. is a science fiction book
a. Frankenstein
25. is the author of “The adventures of Tom Sawyer”.
b. Mark Twain
26. She sent a letter to him last week.
d. personal
27. “His friend looked yesterday. What wrong?
c. awfully
II. Translate into English.
1. Этот роман стоит почитать. This novel is worth reading
2. Кем написана твоя любимая книга? Whom was your favourite book written by?
3. Некоторые книги были запрещены, не так ли? Some books were banned (=prohibited), weren't they?
4. Завтра нас спросят об этом фильме. Tomorrow we will be asked about this film.
5. Письмо было написано до того, как пришла мама. The letter had been written before mother came.
Example: She a student. She’s a teacher.
B isn’t
1 We to France last summer.
C went
2 I always toast for breakfast.
B have
3 your brother play the guitar?
A Does
4 My mum doesn’t like to work.
B driving
5 They TV at the moment.
A ’re watching
6 I to Rome.
B ’ve never been
7 What tomorrow afternoon?
B are you going to do
8 We to Rome and then we drove to Florence.
A flew
9 She to school today because she’s ill.
A doesn’t go
10 I at the moment because I’m on holiday.
A ’m not studying
11 Have you ever Japanese food?
B eaten
12 They pizza. They had pasta.
A didn’t have
13 Who your favourite actors?
B are
14 How often to the cinema?
B do you go
15 They early on Sundays.
C don’t get up
16 This is interesting book. Have you read it?
B an
17 I often go shopping the weekend.
C at
18 The children played in the garden.
C happily
19 These shoes aren’t . Look! They’re too small.
C mine
20 there any biscuits?
A Are
21 She hardly travels abroad.
B ever
22 Paul left work an hour .
C ago
23 How chocolate do you eat?
B much
24 This is film I’ve ever seen.
A the best
25 I’m younger my sister.
B than