问题 选择题

下列图示实验操作中,正确的是(  )

A.A正确

B.B正确

C.C正确

D.D正确

答案

A、闻气体的气味时,防止气体有毒,应用手扇动,不能直接用鼻子凑到瓶口去闻.操作错误.

B、取用块状固体时,先将试管横放,用镊子把固体放在试管口,再让试管慢慢地竖起来.操作错误.

C、如果胶头滴管伸入试管,会造成药品的污染.此操作正确;

D、点燃酒精灯时,用火柴点燃,如果用燃着的酒精灯去点燃另一个酒精灯,会引起酒精失火,造成危险.操作错误.

故选C.

阅读理解

阅读理解。

     Scientists have known for a long time that very loud noises can cause hearing damage or loss (损失).

The noise can be the sound of an airplane or machines in factories or loud music or other common sounds

found at home or at work.

     A famous scientist has found that using aspirin (阿斯匹林) can increase the temporary (暂时的) hearing

loss or damage from loud noises. He did an experiment using a number of volunteers who all had normal

hearing. He gave them different amounts of aspirin for different periods of time, then he tested their hearing

ability. He found that volunteers who were given four grams of aspirin a day for two days suffered (受苦)

much greater temporary hearing loss than those who did not use aspirin. The hearing loss was about two

times as great.

     The scientist said millions of persons in the world use much larger amounts of aspirin than those used

in his experiment. He said these persons may face a serious danger of suffering hearing loss from loud noises.

1. The passage tell us that one's hearing can be damaged (损伤) by_________.

A. the sound of an airplane or machines in factories

B. loud music or other common sounds found at home or at work

C. both A and B

2. Scientists have learned that _________.

A. one may die if he hears a loud noise

B. one may lose his hearing when he hears a terribly loud noise

C. loud noises can only cause damage to the hearing of young people

3. From the passage we know that aspirin _________.

A. can help us to improve our hearing ability

B. makes the temporary hearing damage from loud noises worse

C. makes the temporary hearing damage from loud noises better

4. A large number of people may suffer hearing loss because they_________.

A. take too much aspirin

B. don't realize the bad effect of loud noises

C. never take aspirin

5. Which of the following is true according to the passage?

A. Scientists have just found out that loud noises can't cause hearing damage or loss.

B. The volunteers who took eight grams of aspirin during two days suffered greater

     than those who didn't take aspirin.

C. The scientist did an experiment using volunteers who didn't have normal hearing.

单项选择题