问题 选择题

住宅或商场等地发生火灾时,消防人员用高压水枪喷水灭火,水在灭火中的主要作用是(  )

A.减少空气中氧气的含量

B.降低可燃物的着火点

C.将可燃物的温度降到着火点以下

D.使水分解出不能助燃的气体

答案

A、水枪灭火时,水受热变成水蒸气,水蒸气将可燃物周围的空气排开,从而使可燃物与空气隔绝,使火焰熄灭.当然这不是主要原因.故不选;

B、着火点是物质的固有属性,可燃物的着火点不可改变,该选项中“降低可燃物着火点”的说法是不能实现,水在灭火中只能起到降低温度的作用.故不选;

C、用水灭火时,水降低可燃物的温度,当可燃物温度降至其着火点以下时,可燃物熄灭.该分析正确,故选;

D、水在通电条件下才能分解,况且水分解得到氢气和氧气,氢气可以燃烧、氧气可以支持燃烧,氢气和氧气混合点燃甚至会产生爆炸.所以,此项分析全是想当然没有任何科学道理.故不选.

故选C

选择题
阅读理解

D

“You’re going to the United States to live? How wonderful! You’re really lucky!”

Does this sound familiar? Perhaps your family and friends said similar things to you when you left home. But does it seem true all the time? Is your life in this new country always wonderful and exciting? A great many facts show that it’s not easy for newcomers to adjust to life in a new culture. They have to experience culture shock.

What causes culture shock? Maybe the weather is unpleasant.  Perhaps the customs are different. Perhaps the public service systems such as the telephone, post office, or transportation are difficult to figure out and you make mistakes. The simplest things seem difficult. The language may be difficult. The food may seem strange to you. If you don’t look similar to the natives, you may feel strange. You may feel as ff everyone is watching you. In fact, you are always watching yourself.

Everyone experiences culture shock in some form or another. But culture shock comes as a surprise to most people. A lot of the time, the people with the worst culture shock are the people who never had any difficulties in their own countries. They were active and successful in their community(社区). They had hobbies or pastimes which they enjoyed. When they come to a new country, they do not have the same positions or hobbies as they already had in their countries. They find themselves without a role, almost without an identity. They have to build a new self-image.

Culture shock produces a feeling of disorientation(晕头转向), which may be homesickness, imagined illness, or even paranoia(偏执症). When people feel the disorientation of culture shock, they sometimes feel like staying inside all the time. They want to protect themselves from the unfamiliar environment. They want to create an escape within their room to give themselves a sense of security. This escape does solve the problem of culture shock for the short term, but it does nothing to familiarize the person more with the culture. Familiarity and experience are the long-term ways to settle the problem of culture shock.

67. Who is the passage mainly for?

A. The family and friends of those who came to the US.

B. Those who have got rid of culture shock.

C. People who have just moved to a foreign country.

D. People who can easily adjust their life in the US.

68. The underlined part “you are always watching yourself’” (in Paragraph 3) means         .

A. you are always feeling homesick

B. you are always worried too much about yourself

C. you are always looking at yourself in the mirror

D. you are always nervous about meeting other people

69. Which of the following would be a case of culture shock for newcomers?

A. They have trouble using public telephones.

B. Their positions or hobbies stay the same.

C. They are active and successful in the new community.

D. They have got used to the life in the new country.

70. Which of the following may cause newcomers to lack a sense of security?

A. A new identity.                                      B. Local food.

C. A new serf-image.                                    D. Strange environment.

71. The best way for the newcomers to overcome culture shock is         .

A. to stay inside to protect themselves

B. to make a study of the new hobbies

C. to adapt themselves to the new environment

D. to ask people for help when having difficulties