问题 选择题

下列属于溶液的是(  )

A.把泥沙放入水中

B.澄清的石灰水露置在空气中一段时间

C.医疗上用的葡萄糖溶液

D.治疗扁桃体炎用的青霉素钾溶于水摇匀

答案

A、泥沙不溶于水,不能和水形成均一、稳定的混合物,即不能够形成溶液.故选项错误.

B、澄清的石灰水能与空气中的二氧化碳反应,生成不溶于水的碳酸钙,不能和水形成均一、稳定的混合物,即不能够形成溶液.故选项错误.

C、医疗上用的葡萄糖溶液是均一稳定的混合物,属于溶液;故选项正确;

D、治疗扁桃体炎用的青霉素钾溶于水摇匀后不均一、不稳定,不属于溶液;故选项错误.

故选C.

阅读理解

  We talk about and use the Internet every day, but do you know the history of

the Internet?

  Internet was set up in the 1960s. At that time, computers were large and

expensive. Computer networks didn't work. If there is something wrong with one

computer in the network, the whole networkstopped. So it is necessary to set up a

network system (系统). The network system should be so good that many

different computers can use it. If part of the network was not working,

information could be sent through another part. At first, only the government used

the Internet, but in the early 1970s, universities, hospitals and banks used it,

too.  However, computers were still very , computers became cheaper and easier

to use. Scientists had developed software (软件) andmade it easy to surf the

Internet. Today it is easy to get on-line.

1. According to the passage, we know that_________.

A. the Internet has a very long history          

B. the Internet can work without computer

C. the Internet has a history of about forty years  

D. the Internet is a kind of computer

2. Universities, hospitals and banks have used the Internet for about________.

A. forty years        

B. thirty years        

C. twenty years      

D. fifty years

3. It is very easy to get online because_________.

A. scientists developed software (软件)        

B. computers became cheaper and easier to use

C. the network system is good enough        

D. all above

4. At first, only the ________ used the Internet.

A. government        

B. hospitals        

C. banks and schools      

D. universities

5. The best title of the passage is "_________"

A. The history of computers              

B. The history of the Internet

C. The history of software                

D. People like surfing the Internet

单项选择题