Now you will have two long conversations.

　　Conversation One
　　M: Excuse me, are you waiting to buy concert tickets?
　　W: Yes, I am. So are all these people in front of me.
　　M: Have you been here long?
　　W: About 45 minutes. I’ve moved forward a total of about 3 feet in that time.
　　M: You’re kidding!
　　W: Not at all. There was a couple up ahead of me who got so disgusted they finally gave up and left. They said they’d been waiting for more than an hour.
　　M: Does anyone know what’s causing the delay?
　　W: If so, no one is letting us know. It could be that there aren’t enough people selling tickets this afternoon. Or maybe their computer’s down. I’m sure the concert hasn’t been canceled.
　　M: I just hope they don’t run out of tickets before I get there.
　　W: That really would be annoying, wouldn’t it?
　　M: I guess I should have come before lunch. Or has it been like this all day?
　　W: Apparently it has. In fact, before I came, I tried calling to charge my tickets over the phone, just to avoid this long wait, but they’re not taking phone orders, or checks, or credit cards. It’s cash or nothing. And you have to come in person.
　　M: Well, there’re two more hours before the ticket office closes. Tickets to a good concert are worth waiting for. So I think I’ll just make myself comfortable.

　　Questions 19 to 21 are based on the conversation you have just heard.
　　19.What are the two speakers doing?
　　20.Why did the couple ahead of the woman give up waiting?
　　21.At what time of the day does the conversation most probably take place?

　　Conversation Two
　　W: Ok, last night you were supposed to read an article about human bones. Are there any comments about it?
　　M: Well, to begin with, I was surprised to find out there was so much going on in bones. I always assumed they were pretty lifeless.
　　W: Well, that’s an assumption many people make. But the fact is that bones are made of dynamic living tissue that requires continuous maintenance and repair.
　　M: Right. That’s one of the things I found so fascinating about the article---the way the bones repair themselves.
　　W: Ok. So can you tell us how the bones repair themselves?
　　M: Sure. See, there are two groups of different types of specialized cells in the bone that work together to do it. The first group goes to an area of the bone that needs repair. This group of cells produces the chemical that actually breaks down the bone tissue, and leaves a hole in it. After that the second group of specialized cells comes and produces the new tissue that fills in the hole that was made by the first group.
　　W: Very good. This is a very complex process. In fact, scientists who study human bones don’t completely understand it yet. They are still trying to find out how it all actually works. Specifically, because sometimes after the first group of cells leaves a hole in the bone tissue, for some reason, the second group doesn’t completely fill in the hole. And this can cause real problems. It can actually lead to a disease in which the bone becomes weak and is easily broken.
　　M: Ok, I get it. So if the scientists can figure out what makes the specialized cells work, maybe they can find a way to make sure the second group of cells completely fills the hole in the bone tissue every time. That’ll prevent the disease from ever occurring.

　　Questions 22 to 25 are based on the conversation you have just heard.
　　22. What is the conversation mainly about?
　　23. What is the function of the first group of specialized cells discussed in the conversation?
　　24. What does the woman say about scientists who study the specialized cells in human bones?
　　25. According to the man, what is one important purpose of studying specialized cells in human bones?
转贴于：CET-4考试_考试大

[1] [2] [3] [4] [5] [6]