问题 选择题

下列各组中的物质充分反应后,所得溶液的质量比反应前溶液的总质量减少的是【  】

A.盐酸加入烧碱溶液中

B.锌片浸入硫酸铜溶液中

C.二氧化碳通入足量石灰水中

D.三氧化硫通入氢氧化钠溶液中

答案

答案:C

题目分析:A盐酸加入烧碱溶液中,发生酸碱的中和反应,所得溶液的质量比反应前溶液的总质量增加,,B、锌片浸入硫酸铜溶液中,锌将铜置换出来,锌为65,铜为64,所以溶液质量应该是增加的,  C、 二氧化碳通入足量石灰水中,有碳酸钙沉淀产生,所以质量应该是减小的,D、三氧化硫通入氢氧化钠溶液中,生成硫酸钠,溶液质量是增加的,故选C

单项选择题
阅读理解

     How often one hears children wishing they were grown-up, and old people wishing they were young

again. Each age has its pleasures and its pains, and the happiest person is the one who enjoys what each

age gives him without wasting his time in useless regrets.

     Childhood is a time when there are few responsibilities to make life difficult. If a child has good

parents, he is fed, looked after and loved, whatever he may do. It is impossible that he will ever again in

his life be given so much without having to do anything in return. In addition, life is always presenting new

things to the child—things that have lost their interest for older people because they are too well-known.

But a child has his pains: he is not so free to do what he wishes to do; he is continually being told to do

things, or being punished for what he has done wrong.

     When the young man starts to earn his own living, he can no longer expect others to pay for his food,

his clothes, and his room, but has to work if he wants to live comfortably. If he spends most of his time

playing about in the way that he used to as a child, he will go hungry. And if he breaks the laws of society

as he used to break the laws of his parents, he may go to prison. If, however, he works hard, keeps out

of trouble and has good health, he can have the great happiness of building up for himself his own position

in society.

1. According to Para. 2, the writer thinks that_____.

A. life for a child is comparatively easy

B. a child is always loved whatever he does

C. if much is given to a child, he must do something in return

D. only children are interested in life

2. After a child grows up, he______.

A. will have little time playing

B. has to be successful in finding a job

C. can still ask for help when in trouble

D. should be able to take care of himself

3. Which of the following statements is NOT true according to the passage?

A. People are often satisfied with their life

B. There are fewer interesting things for old people

C. Adults are freer to do what they want to

D. Adults should no longer rely on others

4. The main idea of the passage is_____.

A. life is not enjoyable since each age has some pains.

B. young men can have the greatest happiness if they work hard

C. childhood is the most enjoyable time in one's life

D. one is the happiest if he can make good use of each age in his life.

5. The paragraph following this passage will most probably discuss_____.

A. examples of successful young men

B. how to build up one's position in society

C. joys and pains of old people

D. what to do when one has problems in life