问题 选择题

下列说法正确的是                                                    

A.硫酸、纯碱、醋酸钠和生石灰分别属于酸、碱、盐和氧化物

B.蔗糖、硫酸钡和水分别属于非电解质、强电解质和弱电解质

C.活性炭、SO2和HClO都具有漂白作用,且漂白的化学原理相同

D.硫酸厂厂址的选择应靠近原料产地

答案

答案:B

本题考查物质的分类与性质,及硫酸的综合经济效益;纯碱是碳酸钠的俗名,属于盐类,A错误;活性炭漂白是吸附作用,属于物理变化,SO2漂白是与有色物质结合成无色不稳定的物质,是化合反应,HClO漂白是与有色物质发生氧化还原反应,三者漂白原理不同,C错误;硫酸厂厂址的选择主要是考虑到硫酸的消费问题,即应靠近硫酸消费中心,但由于环保问题,厂址也不适宜建在人群稠密的居民区和环保要求较高的地区,D错误。

单项选择题
阅读理解

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 1960s. 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 part of the network was not working, information could be sent through another part. In this way, computer network system would keep on working all the time.

At first the Internet was only used by the government, but in the early 1970s, universities, hospitals and banks were allowed to use it, too. However, computers were still very expensive and the Internet was difficult to use. By the start of the 1990s, 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 on-line 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 about____________ years.

A.70

B.10

C.50

D.20小题2: A new network system was set up to_____________.

A.make computers cheaper.

B.make itself keep on working all the time.

C.break down the whole network.

D.make computers large and expensive.小题3: At first the Internet was only used by_____________.

A.the government.

B.scientists

C.hospitals and banks

D.schools小题4:Which of the following is TRUE?

A.In the 1960s, computer networks worked well.

B.In the early 1970s, the Internet was easy to use.

C.Sending e-mail is now more popular among students.

D.Today it’s still not easy to get on-line.