问题 选择题

下列物质属于电解质的是(  )

A.铜丝

B.酒精

C.食盐晶体

D.二氧化碳

答案

A、铜丝属于单质,不是化合物,所以不属于电解质,故A错误;

B、酒精在水溶液里不导电,不属于电解质,属于非电解质,故B错误;

C、食盐晶体水溶液里和熔融状态下都能能导电,属于电解质,故C正确;

D、二氧化碳溶于水,二氧化碳与水反应生成了碳酸,碳酸电离出离子能够导电,但是导电的离子不是二氧化碳本身电离的离子,所以二氧化碳不是电解质,故D错误;

故选:C.

单项选择题
阅读理解

阅读理解。

     Education is not an end, but a means to an end. In other words, we do not educate children only for the

purpose of educating them. Our purpose is to fit them for life.

     In some modern countries it has for some time been fashionable to think that by free education for all-one

can solve all the problems of society and build a perfect nation. But we can already see that free education for

all is not enough; we find in such countries a far larger number of people with university degree; they refuse

to do what they think “low” work; and, in fact, work with hands is thought to be dirty and shameful in such

countries. But we have only to think a moment to understand that the work of a completely uneducated farmer

is far more important than that of a professor; we can live without education, but we die if we have no food.

If no one cleaned our streets and took the rubbish away from our houses, we should get terrible diseases in our

towns.

     In fact, when we say that all of us must be educated to fit us for life, it means that we must be educated in

such a way that, firstly, each of us can do whatever work suited to his brains and ability and, secondly, that

we can realize that all jobs are necessary to society, and that is very bad to be ashamed of one's work. Only

such a type of education can be considered valuable to society.

1. The writer of the passage thinks that _____.

A. education can settle most of the world's problems

B. free education for all probably leads to a perfect world

C. free education won't help to solve problems

D. all the social problems can't be solved by education

2. The writer wants to prove that _____.

A. our society needs all kinds of jobs

B. our society needs free education for all

C. a farmer is more important than a professor

D. work with hands is the most important

3. The purpose of education is _____.

A. to choose officials for the country

B. to prepare children mainly for their future work

C. to let everyone receive education fit for him

D. to build a perfect world

4. The passage tells us about _______ of the education.

A. the means

B. the system

C. the value

D. the type