问题 问答题 简答题

简述瓦斯事故及瓦斯爆炸条件。

答案

参考答案:

目前,瓦斯事故已成为我国煤矿“第一杀手”。据统计,1981~2004年全国煤矿瓦斯事故死亡人数占总死亡人数的35.66%;在一次死亡10人以上的特大事故中瓦斯事故发生的次数占全国煤矿各类事故总次数的81.45%,占总人数的80.77%。特别是2004年10月~2005年底,共发生一次死亡100人以上的特别重大瓦斯事故5起,共计死亡757人。因此,预防瓦斯事故的发生是煤矿安全工作的重中之重。

瓦斯爆炸条件有以下3个,且缺一不可:

1.瓦斯浓度

瓦斯爆炸浓度为5%~16%,达到9.5%时爆炸威力最强。但瓦斯爆炸界限会随着其他可燃气体和煤尘的混入,或混合气体的压力和温度的升高而扩大。

2.高温火源

一般情况下,瓦斯引爆温度为650~750℃。明火、煤炭自燃、电气火花、摩擦火花、静电和吸烟等都可能引爆瓦斯。

3.氧气含量

瓦斯爆炸时氧气含量必须达到12%以上。

阅读理解

阅读理解。

                                                           How to Become Fit?

     Healthy eating habit along with regular exercise is the only way to become fit. If you have the correct

number of calories and exercise regularly, you will lose weight, keep fit, and feel great, too.

     During your teenage years, it is important to give your body the energy it needs. If you skip (跳过) meals,

you won't get enough calories, and then you will feel tired. By the way, calorie is just another word for energy.

About 50% of your calories should come from rice, bread, vegetables and fruit. You also need to drink a lot of

water, 6 to 8 glasses a day. Water helps keep your system clean. Drinking enough water will make your skin

better and make you healthy.

     Exercise is something that can help to make you look good, feel good and be healthy. Experts suggest that

teenagers spend at least 30 minutes exercising, five times a week. That is easy to do! You can walk or ride

your bike to school, and do sports at school. However, teenagers often give up sports, saying they have no

time left after their studies. In fact, doing exercise can help them sleep better at night and increase their ability

to focus on their study.

    If you follow the suggestions above, you will look and feel much better and become fit.

1. What's the main idea of this passage?

A. How to eat food.

B. How to exercise.

C. How to lose weight.

D. How to keep fit.

2. The underlined word "calories" means _______ in this passage.

A. 营养

B. 能量

C. 强壮

D. 锻炼

3. Teenagers spend at least _______ minutes exercising a week according to this passage.

A. 150

B. 50

C. 30

D. 5

4. If you _______, you will become fit.

A. exercise regularly

B. drink lots of water

C. eat rice, bread, vegetables and fruit

D. have a healthy eating habit along with regular exercise

5. Why do teenagers give up sports in school according to this passage? Because they _______.

A. are lazy

B. feel great

C. are busy with their studies

D. don't like sports

选择题