下列装置所示的实验中，能达到实验目的是（ ） A．检查装置气密性 B．用乙醇提

消防队员在某高楼进行训练，他要从距地面高h=36m处的一扇窗户外沿一条竖直悬挂的绳子滑下，在下滑过程中，他先匀加速下滑，此时手脚对悬绳的压力F_Nl=640N，紧接着再匀减速下滑，此时手脚对悬绳的压力F_N2=2080N，滑至地面时速度恰为0．已知消防队员的质量为m=80kg，手脚和悬绳间的动摩擦因数为μ=0.5，g=10m/s²，求：

（1）分别求出他在加速下滑、减速下滑两过程中的加速度大小？

（2）他沿绳滑至地面所用的总时间t？

小敏、晓冬、贝贝三人的平均年龄是9岁，小敏、贝贝两人的平均年龄是10岁．那么晓冬的年龄是______岁．

Industrial pollution is not only a problem for the countries of Europe and North America but also an extremely serious problem in some developing countries. For these countries, economic growth is a very important aim. They want to introduce industries, and so they put few controls on the industries which cause pollution.
Cubatao, an industrial town of 85 000 people in Brazil, is an example of the connection between industrial development and pollution. In 1954, Cubatao had no industry. Today it has more than twenty large factories, which produce many pollutants. The people of the town are suffering from the poisonous matter in their environment and the bad effects can be clearly seen. Birth shortcomings are extremely common. Among children and adults, lung problems are sometimes twelve times more common in Cubatao than in other places.
It is true that Brazil, like many other countries, has laws against pollution, but these laws are not enforced strictly enough. It is cheaper for companies to take no notice of the laws and pay the fines than to buy the expensive equipment that will reduce the pollution. It is clear, therefore, that economic growth is more important to the government than to the health of the workers. However, the responsibility does not completely lie with the Brazilian government. The example of Cubatao shows that international companies are not acting in a responsible way either. A number of the factories in the town are owned by large companies from France, Italy, and the US. They are doing things in Brazil that they would not be able to do at home. If they caused the same amount of pollution at home, they would be severely punished or even put out of business.

How is the health of the population of Cubatao

A. There are more heart diseases among people who live near chemical factories.
B. More people suffer from lung diseases because of poisonous matter.
C. Their health is affected by pollutants the same way as that of other Brazilians.
D. Babies there are found not as bright as those who live in other places.

听觉疲劳指（）

A.短时间暴露于强噪声，使听阈上升10~15dB，脱离噪声接触后数分钟内即可恢复正常

B.较长时间暴露于强噪声，致使听阈上升超过15~30dB，脱离后需数小时至几十小时才能恢复

C.长期在强噪声环境中工作，导致听力曲线在3000~6000Hz范围内出现"V"改变

D.长期接触强噪声引起听力曲线从低频到高频呈斜形逐步下降

E.听力曲线各频段以同等程度水平下移

简述汗法的临床应用和代表方剂。