单选题 Questions 19 to 22 are based on the conversation you have just heard.

A、 How bones continuously repair themselves.
B、 The chemical composition of human bones.
C、 Two different types of bones in the human body.
D、 How bones help the body move.

【正确答案】 A

【答案解析】[听力原文] 19-22
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. (19)But the fact is 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 bones repair themselves.
W: OK. (19) 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. (20) 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, (21)the 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. (22)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 will prevent the disease from ever occurring.

19. What is the discussion mainly about?

对话一开始提出人类骨骼的问题，女士说“But the fact is bones are made of dynamic living tissue that requires continuous maintenance and repair.”继而又提出“So can you tell us how the bones repair themselves?”后面都是针对该话题展开的讨论，所以整个对话主要讨论的是骨骼的自我修复能力。
[问题类型] 主题归纳题
[相关信息] article about human bones, how the bones repair themselves

A、 They defend the bone against viruses.
B、 They prevent oxygen from entering the bone.
C、 They connect the bone to muscle tissue.
D、 They break down bone tissue.

【正确答案】 D

【答案解析】[听力原文]
What is the function of the first group of specialized cells discussed in the talk?

男士解释了第一组细胞的作用，第一组细胞生成一种化学物质分解骨组织(This group of cells produces the chemical that actually breaks down the bone tissue...)，由此可见答案是They break down bone tissue.
[问题类型] 细节理解题
[相关信息] 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

A、 They have difficulty identifying these cells.
B、 They've found similar cells in other species.
C、 They've learned how to reproduce these cells.
D、 They aren't sure how these cells work.

【正确答案】 D

【答案解析】[听力原文]
What does tile professor say about scientists who study tile specialized cells in human bones?

女士说这种特殊细胞作用于人类骨骼的过程相当复杂，In fact，the scientists who study human bones don't completely understand it yet.所以答案是这些科学家也不完全知道这些细胞如何工作。
[问题类型] 细节理解题
[相关信息] ...the scientists who study human bones don't completely understand it yet

A、 To find out how specialized bone ceils have evolved.
B、 To understand differences between bone tissue and other tissue.
C、 To learn how to prevent a bone disease.
D、 To create artificial bone tissue.

【正确答案】 C

【答案解析】[听力原文]
According to the student, which is one important purpose of studying specialized cells in human bones?

学习这些人类骨骼巾的特殊细胞的重要目的是为了学习如何预防骨头疾病。从男士的话“That will prevent the disease from ever occurring”可以得出答案。
[问题类型] 细节理解题
[相关信息] That'll prevent the disease from ever occurring.