密码学家W．Diffie与M．Hellman在1976年创新性地提出了公钥体制的概念，以期解决（）

W: Excuse me, sir, is there a problem?

M: WelI, yes, I don't really understand it. When I put my card in, the machine ate it.

W: Ate it ? You mean it didn' t give it back?

M: Yes, that' s right. It kept it.

W: Did you press the withdrawal button and the amount you want?

M: Yes.

W: How about your secret code? Did you enter your number?

M: Well ... come to think of it, it did ask me three times to enter my code.

W: Are you sure you entered your correct number?

M: Hmm, I think se, but maybe I made a mistake.

W: I see. Well, you probably entered the wrong number. When a machine receives a wrong number three times it automatically keeps the card.

M: Oh, I didn't know that. So how do I get another card?

W: That' s no problem ... first you need to fin in a form. so we can get you a new one. Could you come over to the counter?

M: Very sorry about that.

W: OK, please fill this in with your account number and today's date. Then we can issue you a new card. You'll get it in about a week.

M: OK, thanks very much, and I' m sorry for the trouble.

W: Not at all, sir. And when you receive your new card, it' s a good idea to memorize the number or make a note of it somewhere.

M: Right, I'll do that.

(23)

A．Library

B．Shop

C．Bank

D．Supermarket

M: Hi, Lisa. How’s life on campus?

W: Hi, John. Oh not so had. Pretty good in fact.

M: Is that what you think? I mean, do you like living on campus?

W: Yeah, I enjoy living here because there' s so many people around and it' s easy to make friends. Wliat about you? Have you ever lived in a dorm before?

M: No, this is the first time.

W: I think you'll find it quite convenient. The library, labs, sports center and other facilities are fight on campus.

M: That' s true. The atmosphere here is different from the outside. But I guess living in town has its advantages too, like being close to the shopping center. You know, our university is so far from downtown.

W: But the commuting to classes... I mean, you would have to get up so early to get to classes on time. And then going home would be so much time.

M: Yeah, but the food here...it seems it's the same thing in the cafeteria every day.

W: Well, I think the food here is OK, and if you want a change, you can eat out once in a while.

M: True.

(20)

A．She thinks it' s easy to make friends.

B．She likes to eat in the cafeteria.

C．She can save a lot of time.

D．She likes being close to the shopping center.

M: Why?

W: I'm answering the phone.

M: OK. I will do it.

What's the woman doing?

A．She is watching TV.

B．She is telephoning.

C．She is turning the television down.

M: It's supposed to clear up this week.

What are the speakers talking about?

A．A man.

B．The weather.

C．An exam.

W: Have you heard the good news, Henry?

M: What's that?

W: It's going to be cold tonight and tomorrow there will be snow.

M: No, I hadn't heard. Why do you think that's good news, Gene?

W: That means that this weekend I'll be up in the mountains skiing.

M: Well, there is that. Is there going to be a lot of snow in the mountains?

W: The news said that there would be a storm and that by the weekend there would be 14 inches of snow up there.

M: Wow! That's a lot of snow. I might decide to go up to the mountains too. Do you think that the roads will be clear?

W: They said that the snow will be finished by Thursday night so that would give them Friday to clear the roads. I'm planning to put snow tires on my car, so I shouldn't have any problem driving up to the skiing area. Do you want a ride?

M: That would be great. I'll pay for half of the gas. When will you leave?

W: I'll plan on leaving Friday afternoon after class. It takes about four hours to drive there, so I should get there by eight or nine o'clock.

M: Good. That way we can be out on the mountain and ready to ski early on Saturday morning.

W: I'll see you Friday afternoon. Don't forget your skis.

(20)

A．Gene and Henry can swim.

B．Gene does not like cold weather.

C．It is going to snow tomorrow.

D．Gene has snow tires on his car.

M：I'm waiting for a phone call．

Q：What does the man imply?

(10)

A．He is going to call somebody.

B．He will join the woman.

C．He isn't going to the cinema.

D．He is not interested in the movie.

A.人到人(MantoMan)

B.人到机器(MantoMachine)

C.机器到人(MachinetoMan)

D.机器到机器(MachinetoMachine)