问题 选择题

2011年9月27日中国“神舟八号”飞船成功进入太空.偏二甲肼(化学式C2H8N2是火箭推进器的常用燃料,下列有关偏二甲肼的说法错误的是(  )

A.一个偏二甲肼分子由12个原子构成

B.偏二甲肼分子中碳、氢、氮原子个数比为1:4:1

C.偏二甲肼由碳元素、氢元素和氮元素组成

D.偏二甲肼分子中存在一个氮分子

答案

A、偏二甲肼C2H8N2分子中含2个C原子、8个H原子和2个N原子,共12个原子,故A正确;

B、偏二甲肼C2H8N2中碳、氢、氮原子个数比2:8:2=1:4:1;故B正确;

C、偏二甲肼C2H8N2是由碳、氢、氮三种元素组成的,故C正确;

D、偏二甲肼含C、H、N三种元素,其分子中含2个C原子、8个H原子和2个N原子,偏二甲肼不含氮气,故D不正确.

故选D.

问答题 论述题
阅读理解

The best way of learning a language is using it. The best way of learning English is talking in English as much as possible. Sometimes you'll get your words mixed up (混合) and people will not understand you. Sometimes people will say things too quickly and you can't understand them. But if you keep your sense of humor, you can always have a good laugh at the mistakes you make. Don't be unhappy if people seem to be laughing at your mistakes. It's better for people to laugh at your mistakes than to be angry with you, because they don't understand what you are saying. The most important thing for learning English is: "Don't be afraid of making mistakes because everyone makes mistakes."

1. The writer thinks that the most important thing for you to learn a language is___________.

A. reading      B. writing     C. using     D. listening

2. What should you do in learning English?

A. Try to make some mistakes.              B. Avoid making any mistakes.

C. Remember as many new words as you can.  D. Use it as often as you can

3. If people laugh at the mistakes you make, you should ___________.

A. be angry with them                 B. be angry with yourself

C. not care                          D. believe you are right

4. When you make a mistake, you should___________.

A. never make any mistakes again     B. tell others not to make the same mistake

C. punish yourself for making it       D. keep your sense of humor

5. The story tells us:" ___________."

A. It is normal (正常的) that we make some mistakes in learning English

B. Everyone must make mistakes

C. We can avoid making mistakes in learning a language

D. Laughing can help one learn English well