问题 选择题

对下列现象或做法的解释,不正确的是(  )

A.用警犬搜救地震中被埋人员--分子在不断运动

B.液态水变成冰--水分子间间隔消失

C.食物腐败--分子发生了变化

D.氢气和液氢都可做燃料--同种物质的分子,化学性质相同

答案

A、用警犬搜救地震中被埋人员,是因为人体气味中含有的分子是在不断的运动的,向四周扩散,使警犬闻到人体气味,故选项解释正确.

B、液态水变成冰,是因为水分子间的间隔变小了,而不是消失了,故选项解释错误.

C、食物腐败的过程中有新物质生成,分子本身发生了改变,故选项解释正确.

D、氢气和液氢都可做燃料,是因为它们是由氢分子构成的,同种物质分子的化学性质相同,故选项解释正确.

故选B.

选择题
阅读理解

阅读理解。

      "How are you?" is a nice question. It's a friendly way that people in the United States greet each other.

But "How are you?" is also a very unusual questin. It's a question that often doesn't have an answer. The

person who asks "How are you?" hopes to hear the answer "Fine.", even if the person's friend isn't fine.

The reason is that "How are you?" isn't really a question and "Fine." isn't really an answer. They are simply

other ways of saying "Hello!" or "Hi!". 

      Sometimes, people also don't say exactly what they mean. For example, when someone asks, "Do you

agree?", the other person might be thinking, "No, I disagree. I think you're wrong …" But it isn't very polite

to disagree strongly, so the other person might say "I'm not sure …". It's a nice way to say that you don't

agree with someone.

      People also don't say exactly what they are thingking when they finish talking with other people. For

example, many talks over the phone finish when one person says "I've to go now." Often, the person who

wants to hang up gives an excuse, "Someone is at the door." "Something is burning on the stove."  The

excuses might be real, or it might not. Perhaps the person who wants to hang up simply doesn't want to

talk any more, but it isn't polite to say that. The excuse is more polite, and it doesn't hurt the other person.

      When they are greeting each other, talking about an idea, or finishing a talk, people often don't say

exactly what they are thinking. It's an important way that people try to be nice to each other, and it's also

a part of the game of language.

1. When a person in the United States asks "How are you?", he or she wants to hear "______". [ ]

A. How are you?

B. Hello!

C. I don't know.

D. Fine.

2. When a person wants to disagree with someone, it is polite to say "______". [ ]

A. You're wrong. I disagree.

B. I'm not sure.

C. I'm sure I disagree.

D. No, I disagree.

3. When a person says "I've to go now. Someone is at the door.", he or she may be ______. [ ]

A. giving an excuse

B. hurting someone's feeling

C. talking to a person at the door

D. going to another place

4. One of the rules of the game of language is probably "______". [ ]

A. Always say what you mean.

B. Don't disagree with people.

C. Never say exactly what you're thinking.

D. Be polite.