问题 问答题

如图所示,大口玻璃瓶内有一些水,水的上方有无色水蒸气.给瓶内打气,当瓶塞“砰”地跳出时,瓶内出现白雾.

(1)白雾的形成原因是:______(从物态变化角度回答);

(2)简要说明瓶塞跳出、发声的过程中,瓶内空气的内能的变化情况:

______.(须说明内能大小变化及改变方式))

答案

雾是小水滴,它是由水蒸气的液化而形成的.其具体过程是:瓶内的气体压强增大到一定程度,对瓶塞做功,将瓶塞打出,气体对外做功,将内能转化为机械能,气体的内能减少,温度降低,瓶中的水蒸气遇冷液化而形成白雾.

故答案为:(1)瓶内水蒸气降温液化形成小水珠悬浮在空气中形成白雾.

(2)以做功的方式改变内能,(内能转化为机械能,)内能减小.

阅读理解

One suicide and three attempted ones that left two seriously injured, all by middle school students in Shanghai last week, cast a gloom (忧郁) over an otherwise happy beginning of a new term there. The terrible things took place even as the Ministry of Education and China Central Television organized the first lesson on TV about personal safety for students last Monday, the first day of the new semester. Such things suggest that this first lesson is more than necessary. Not only should kids be taught how to protect themselves in times of emergency, they should also be made aware of the value of tile2 One student was prevented from killing himself from his school building. He said he just could not accept the fact of not being able to go tip to a higher grade with his classmates, and thus considered life meaningless. Another 12-year-old boy who jumped off a building to his death was said to have been a good student, and no one could say why he chose to end his life. Obviously, their inner worlds were seriously affected. But when they chose to take their own lives, their irresponsible choice was clearly the result of a lack of adequate understanding of the value of life.

The ancient sage Confucius (孔子) stressed that one must protect even one's hair and skin from being hurt. He meant that the sense of responsibility for one's parents was important as far as the value of life was concerned. When we talk about the enthusiasm of making contributions to our motherland, we are referring to values that constitute the nobler part of the meaning of life. The value of life should be far beyond the concern for personal interest.

Undoubtedly, those kids who chose to take their own lives were faced only with their own sadness that they could not overcome. If they had a little concern for their parents, for their parents' expectations of them or for their own potential contributions to this world in the future, they would not have gone that far. Difficulties or sufferings are supposed to help kids develop their sense of responsibility and thus help them better understand the value of life.

Too much attention and care from their parents and grandparents have made most of the only children self-centered. Many think it is natural that they deserve to be taken care of by others in whatever way they want. They expect to have their problems solved by their parents or someone else. With such a false sense, they fail to grasp the tough reality of life. They suffer from the illusion (幻觉) that their life should be nothing but plain sailing, Whenever the illusion is broken, they can hardly gather enough courage to face life as it is. So a hotline is indeed necessary to help those kids who find it hard to accept the tough reality of life. But parents and teachers also need to take lessons from the things. They need to know that life should not always be sugar-coated for kids; they should be made to taste the bitter side too as early as possible.

小题1:From the passage we know that _________.

A.four students took their lives in Shanghai last week

B.being unable to catch up with other classmates led to the 12-year-old boy killing himself

C.the importance of life lies in the sense of responsibility for parents

D.parents are supposed to tell the kids the bitter side of life as well as the sweet side小题2:What mainly causes those kids to take their own lives is that _________.

A.they are worried that they may fall behind others in studies

B.they lack the respect for their parents

C.they may be physically healthy, but mentally unhealthy

D.their parents expect too much from them小题3:Which of the following would be the best title of the passage?

A.An irresponsible choice.

B.The value of life.

C.Weak-minded generation.

D.The reality of life.

单项选择题 A2型题