问题 填空题

下列变化中,属于燃烧的是______,属于爆炸的是______,属于缓慢氧化的是______,属于由缓慢氧化而引起自燃的是______.

A.食物的腐败

B.擦机器的棉纱因堆放不合理,时间长了会着火燃烧

C.把灼热的细铁丝伸入氧气瓶中

D.给浸渍了液态氧的木屑或木炭粉点火.

答案

把灼热的细铁丝伸入氧气瓶中,细铁丝会燃烧起来.故填:C

把浸透了液态氧的木屑或木炭粉点火会发生爆炸.故填:D

动物的呼吸、食物的腐败、铁器在空气中锈蚀都是比较缓慢的氧化反应,属于缓慢氧化.故填:A

擦机器的棉纱因堆放不合理,时间长了会着火燃烧是因为擦机器的棉纱不断进行着缓慢氧化放出热量,使棉纱温度升高,当达到棉纱的着火点是可燃物自行燃烧起来,这就是自燃.故填:B

阅读理解

阅读理解。

     Very few people enjoy exams. I don't, either. And although I tell myself not to worry about them, I always

do! So I am not surprised that my students worry about them, too, even though they usually don't need to.

Because they are afraid of failing. However, since it is hard not to worry at all, we all must try not to worry

too much. Why? Because worrying makes exams worse! How to do this?

     1. Ask the teacher about how to revise and about exam skills- how to work when you are in the exam.

     2. Good students don't wait until the week before an exam. They study all through the year. It is not

possible to learn everything at the last minute. So don't leave it till then!

    3. If you start planning and working for each exam early and you make sure that you understand what

you are studying, then, when it is over, you'll be able to say, "What a good exam that was!"

     4. Take a short rest during your time of work and revision. If your mind is tired, it will not remember well.

Work at the time when you know you will work at your best.

     5. If you are studying in the evening, don't go straight to bed afterwards. Your mind will still be "going

round and round" - thinking too much. Do something else, maybe walk or get exercise. Choose something

that will relax you, and make you think of other things.

    6. If you feel bad, talk to someone about your worries. But don't be too relaxed! Some stress over exams

makes you work hard for them.

1. How does the writer feel about exams?

A. Excited.

B. Bored.

C. Worried.

D. Surprised.

2. Why are the students afraid of exams?

A. Because they are afraid of failing.

B. Because they want to get full marks.

C. Because exams are usually hard.

D. Because they think their teachers will be angry with them they can't pass the exams.

3. Which is NOT mentioned (提到) in the passage?

A. Good students don't wait until the week before an exam.

B. Start planning and working for each exam early.

C. If you don't know how to work for an exam,ask the teach about it.

D. You should sleep well before the exam.

4. According to the passage, if you feel bad, you'd better ______.

A. take a short rest

B. tell someone about your worries

C. walk or get exercise

D. keep busy working and forget your worries

5. The writer of the passage is probably a ______.

A. student

B. teacher

C. journalist

D. scientist

单项选择题