问题 多选题

下列①、②、③、④所述的四种情境:

①点火后即将升空的火箭;

②高速公路上沿直线高速行驶的轿车为避免事故紧急刹车;

③运行的磁悬浮列车在轨道上高速行驶;

④太空的空间站在绕地球匀速转动.

请根据所学知识从A、B、C、D四个选项中选择对情境的分析和判断正确的说法(  )

A.因火箭还没运动,所以加速度一定为零

B.轿车紧急刹车,速度变化很快,所以加速度很大

C.高速行驶的磁悬浮列车,因速度很大,所以加速度也一定很大

D.尽管空间站做匀速转动,但加速度也不为零

答案

A、火箭点火启动时,初速度是v1为零,但是下一时刻速度v2不为零;因为a=

△v
△t
,所以加速不为零.故A错误.

B、轿车紧急刹车,说明速度变化很快,所以加速度很大.故B正确.

C、高速行驶的磁悬浮列车,速度很大,但是完全可以做匀速直线运动,所以加速度也可以为零.故C错误.

D、空间站匀速转动,需要向心力,加速度为向心加速度.故D正确.

故选:BD

单项选择题
阅读理解

You feel generally depressed and unable to concentrate. Your pattern of daily activity may change:you find yourself awake and active in the middle of the night;you sleep late into the day.  You stay in your room and have little contact with people except with those who speak your language. In your mind,you criticize the people around you;You are constantly comparing between life here and the perfect life back home. Above a11, you are homesick almost all the time.

If you ever find yourself behaving in these ways,you are probably suffering from culture shock. Culture shock is a psychological condition that sometimes has physical effects. It affects people who have moved away from an environment where they know how to live into a new environment where much is unfamiliar to them-the food,the weather, the language,and especially the unwritten rules for social behavior.

Culture shock is caused. therefore,by a lack of familiarity with the system of rules that the new society uses for everyday living. Language is an obvious example of one type of these rules. If your language is limited,even the simplest task can suddenly become difficult for you. However, knowledge of the language doesn’t make you free from the effects of culture shock as many Britons in the United States and many Americans in Britain will experience. Most people are unaware that each culture has its own rules for social behavior;they certainly think that polite, civilized people behave the same way worldwide. This mistaken belief will cause you to behave and judge the behavior of others according to the rules you learned as a member of your own culture. If the rules are different, then people will misunderstand your behavior, and you will misunderstand theirs.

How can you deal with culture shock? First, you need to realize that every newcomer suffers from some culture shock. You’re not the only case. Second,remember that culture shock can be cured. The process of recovery will start as you begin to become used to the new culture. Of course learning the language will help remove the obstacles to communication and will ease the job of making Mends with people. Recognizing and learning the new cultural rules of behavior, however, may be just as important. You’ll still have emotional reactions to unfamiliar situations but you’11 find yourself making jokes about them rather than condemning the entire society as “stupid.” The jokes are a good sign:they show that you are recovering.

小题1:What’s the main idea of the first paragraph?

A.the causes of culture shock

B.some signs of culture shock

C.the cure for culture shock

D.an explanation of culture shock小题2:What does the underlined word obstacles mean?

A.things that make a task easy

B.things that make at ask enjoyable

C.things that make a task difficult

D.things that make at ask funny小题3:What can be concluded when you find yourself making jokes about new culture?

A.You are about to recover from culture shock.

B.You have completely got rid of culture shock.

C.You never suffered from culture shock before.

D.You’re in culture shock for many years.小题4: Which of the following statements is true according to the passage?

A.The passage suggests that culture shock makes you miss your family badly.

B.A good knowledge of the language will prevent you suffering from culture shock.

C.In the writer’s opinion,the social rules for polite,civilized behavior are international.

D.If you have a perfect knowledge of their language, you will never be misunderstood.