问题 选择题

极少数青少年有吸烟的坏习惯.香烟燃烧的烟气中有许多强致癌物质,其中对人体危害最大的是尼古丁[C10H14N2]、焦油、一氧化碳等,下列说法错误的是(  )

A.吸烟严重危害人的身心健康

B.尼古丁由碳、氢、氮元素组成

C.尼古丁中碳、氢、氮元素的质量之比为10:14:2

D.一氧化碳能与血液里的血红蛋白结合,有剧毒

答案

A、香烟的烟气中含有一氧化碳、尼古丁、焦油等有害物质,吸烟有害健康是人们的共识,故选项说法正确.

B、根据尼古丁的化学式C10H14N2可知,尼古丁是由碳、氢、氮三种元素组成的;故选项说法正确.

C、根据尼古丁的化学式C10H14N2可知,碳、氢、氧三种元素的质量比为(12×10):(1×14):(14×2)=60:7:14;故选项说法错误.

D、一氧化碳由剧毒是因为它能与血液中的血红蛋白结合,使人缺氧中毒.故选项说法正确.

故选C.

阅读理解

阅读理解

阅读下面短文,从每题所给的A、B、C、D 四个选项中选出最佳选项。

     Cindy, Jerry and Mary are giving their opinions about a good friend.  

Cindy: I think a good friend should be honest(诚实的). That's more important than any other things

and is where a good friendship starts. If a friend isn't honest, he may lose his friends' trust.

Jerry: I think a good friend has to be generous. Here "generous" doesn't mean he has to give  his

friends his lunch money or his clothes. It means he should share(分享) his ideas and feelings with

his friends. In fact, his friends can know him better in this way.

Mary: In my opinion, a good friend should understand his friends. When there's  something

wrong between him and his friends, he must put himself in his friends' place and  think more for his

friends.

1. What does the underlined sentence(句子) mean?

A. To be honest is the most important.  

B. To be honest is as important as other things.

C. To be honest is not so important.    

D. Honest people g et more things than others

2. Jerry would like to make friends with people who ______.

A. give him lunch money

B. know him very well

C. tell him their ideas and feelings

D. give him some clothes

3. Mary thinks friends should ______.

A. visit each other often

B. go to more places to play

C. understand each other

D. help each other do more things

4. Which of the following is NOT true?

A. These three people are talking about what they think a good friend should be.

B. Cindy thinks to be honest is the base(基础) of a good friendship.

C. Mary would like to make friends with people who think more for friends.

D. A man is generous. That means he is very clever.

5. What does the underlined word "trust" mean in Chinese?

A. 夸奖        

B. 批评    

C. 理解        

D. 信任

判断题