来自：查字典高考网 2014-12-25
2002年5月托福听力文字
Part B
31－34
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 were so much going on in bones. I always assumed they were pretty lifeless.
W： Well， thats an assumption many people make. But the fact is bones are made of dynamic living tissue that requires continuous maintenance and repair.
M： Right. Thats 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 produce 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 produce 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， the scientists who study human bones dont 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 doesnt 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. Thatll prevent the disease from every occurring.35－38M： Hi Diana， mind if I sit down？W： Not at all， Jerry. How have you been？M： Good. But Im surprised to see you on the city bus. Your car in the shop？W： No. Ive just been thinking a lot about the environment lately. So I decided the air will be a lot cleaner if we call use public transportation when we could.M： Im sure you are right. The diesel bus isnt exactly pollution free.W： True. Theyll be running a lot cleaner soon. We were just talking about that in my environmental engineering class.M： What could the city do？ Install pollution filters in all their buses？W： They could， but those filters make the engines work harder and really cut down on the fuel efficiency. Instead they found a way to make their engines more efficient.M： How？W： Well， there is a material called XXX. Its a really good insulator. And a think coat of it get sprayed on the certain part of the engine.M： An insulator？W： Yeah. What it does is reflect back the heat of burning fuel. So the fuel will burn much hotter and burn up more completely.M： So a lot less unburning fuel comes out to pollute the air.W： And the bus will need less fuel. So with the saving on fuel cost， they say this will all pay for itself in just six months.M： Sounds like people should all go out and get some this stuff to spray their car engines.W： Well， its not really that easy. You see， normally， the materials are fine powder. To melt it so you can spray a coat of it on the engine parts， you first have to heat it over 10，000 degrees and then， well， you get the idea. Its not something you or I be able to do ourselves.
【2002年5月托福听力文字】相关文章：
[标签：海外留学,考试,托福,,]
1000张学生用草稿纸考研专用免邮空白便宜薄演草演算纸白纸本书写纸批发打草a4大张实惠装18k高考数学草稿本
高考前必听的5首励志歌曲，《Dream it possible》最能鼓舞人心！
探秘历史 第二季 第479集 河南叛逆高考生，写下8000字批判作文，现状如何？
amc传媒音乐影像 第一季 第600集 高中校长演唱《记忆花园》为高考学子助力打气
爆笑班主任 第一季 第220集 高考前最后一只视频，山东王老师揭秘高考的秘密
加油吧考生：2019高考咨询大直播 第43集 科学填报志愿 规划精彩人生
NBA流言收割机 第6集 神预测？高考数学试题暗示猛龙勇士4
美术联考用纸上海考试模拟试卷纸高考统考纸 4k水粉纸素描纸 速写纸卡纸美术模拟测试试卷纸 美术考试专用纸
沈阳音乐学院郎亦农教授的女高音高考曲目解析课程 第9集 《赛吾里麦》演唱讲解，音乐表现一定要自然流畅
广州早晨 2019 山西一高中班主任带学生骑行1800公里去上海
