处理障碍更换的光缆长度一般不应小于（）。A、100 B、200 C、300 D、40

We are all busy talking about and using the internet. But how many of us know the history of the internet?

Many people are surprised when they find that the internet was set up in the 1960’. At that time, computers were large and expensive. Computer networks didn’t work well if one computer in the network broke down. Then the whole network stopped. So a new network system had to be set up. It should be good enough to be used by many different computers. If one part of the network was not working , information could be sent through another part. In this way computer network system could keep on working all the time.

At first the internet was only used it, too. However, computers were still very expensive and the internet was difficult to use. By the start of the 1990’s, computers were still very expensive and the internet was difficult to use. By the start of the 1990’s, computers had become cheaper and easier to use. Scientists had also developed software that made “surfing “ the internet more convenient.

Today it is easy to get online and it is said that millions of people use the internet every day. Sending e-mail is more and more popular among students. The internet has now become one of the most important parts of people’s life.

小题1:The Internet has a history of more than        years.

A．ten

B．twenty

C．forty

D．sixty小题2:A new network system was set up to        .

A．make computers cheaper

B．make computers expensive

C．make itself keep on working all the time

D．make computers large小题3:At first the Internet was only used by        .

A．the government

B．universities

C．hospitals

D．schools小题4:What does “convenient” mean in the passage?

A．便宜的

B．昂贵的

C．方便的

D．困难的小题5:Today        than before.

A．fewer people are using computers

B．it is more difficult to get online

C．sending e-mail is more popular

D．computers are more expensive

My brother _______ the army two years ago.He has ______ for two years.

A．joined in ; joined

B．joined ; been a soldier

C．joined in ; become a soldier

D．joined; joined in

以下哪种药物较易引起白细胞减少

A．氯丙嗪

B．氯氮平

C．奋乃静

D．氟哌啶醇

E．三氟拉嗪

下列属于企业宏观营销环境的是（）。

A.顾客

B.竞争者

C.供应商

D.政治与法律环境

下列细胞能成功用于做质壁分离实验的材料的是（）

A.人的口腔上皮细胞

B.洋葱根尖分生区细胞

C.叶的下表皮细胞

D.用开水煮过的洋葱鳞片叶紫色外表皮细胞