问题 选择题

下列有关钢铁的叙述不正确的是

A.生铁和钢都属于铁合金

B.铁丝在氧气中燃烧生成Fe2O3

C.在钢管表面镀锌可以防止锈蚀

D.炼铁的主要原料有铁矿石、焦炭、石灰石

答案

答案:B

题目分析:A、生铁和钢都属于铁合金,正确,B、铁丝在氧气中燃烧生成Fe3O4,错误,C、因为锌的活动性比铁强,故在钢管表面镀锌可以防止锈蚀,错误,D、炼铁的主要原料有铁矿石、焦炭、石灰石,正确,故选B

阅读理解

阅读理解。

     Some people say that laughter is the best medicine. Scientists are studying laughter carefully and finding

it is really good for us.

     What happens when we laugh? We use fifteen different muscles in our face, and laughing is food for our

body. When we laugh, we breathe quickly and exercise the face, shoulders and chest. Our blood pressure goes

down, and our circulation gets better. Our heartbeat is lower. Our brain makes a natural painkiller.

      Every minute we laugh is the same as forty-five minutes' relaxation. Many doctors around the world believe that laughter helps us get better when we are sick.

      Of course, there are many kinds of laughter. Different people have different laughters. We may change the way we laugh in different situations. But everyone has his own way to laugh. How do you usually laugh?

1. Laughter is good for us, and _____.

A. everybody thinks so

B. doctors say so

C. scientists are studying it

D. everyone likes laughing

2. When we laugh, we exercise _____.

A. fifteen muscles of- the face

B. fifteen muscles of the chest

C. every place of our body

D. fifteen organs of our body

3. Laughter makes a natural painkiller _____.

A. in our shoulders

B. in our heart

C. in our brain

D. in our blood

4. One-minute laugh equals 45-minute _____.

A. exercise

B. rest

C. thinking

D. sports

5. According to the passage, _____.

A. people laugh in the same way

B. one should learn different ways of laughing

C. we need to laugh forty-five minutes each day

D. everyone has his own way of laughing

单项选择题