问题 选择题

如图所示,把锌片和铜片用导线相连后插入稀硫酸构成原电池.下列叙述正确的是(  )

A.一段时间后溶液变蓝

B.Cu是负极,Cu被氧化

C.电子从锌片经外电路流向铜片

D.铜片上可见气泡,一段时间后溶液总质量减少

答案

A、原电池反应是锌和稀硫酸反应生成硫酸锌和氢气,无铜离子生成,故A错误;

B、铜在原电池中做正极被还原,故B错误;

C、原电池中电子从负极锌经导线流向正极铜,故C正确;

D、铜片上氢离子得到电子生成氢气,锌和稀硫酸反应生成氢气,溶液质量增加,故D错误;

故选C.

阅读理解

What do people do with their old, out-of-date but still useful computers? Most people don’t know what to do with them. Many old computers are put away in homes. Many more are simply thrown out with the rubbish.  

Some companies are thinking of ways to bring down the number of old computers. Sony has agreed to help recycle old Sony products. Dell, Hewlett-Packard and other companies now also take back some old computers.  

In some countries, laws are being passed, too. Computer companies will have to collect and recycle their used products. And 70% of computer waste must be recycled. The idea behind the laws is that computer companies themselves should pay the cost. That will encourage them to make computers that are easier and cheaper to repair and upgrade(升级).  

Yet while many people are throwing away good computers, others cannot afford them at all. Hundreds of organizations are working to solve this problem. They collect and repair old computers. Some also teach others how to repair computers.  

The computers then go to schools, charities and people who need them. Giving a used computer to one of these organizations can turn one person’s rubbish into someone else’s useful things—and cut down on waste, too.  

小题1: How do people usually deal with their old computers?  

A. They stop using them. B. They give them to others.   C. They fix them up.  

小题2: What do some computer companies do to bring down the number of old computers?  

A. They don’t do anything about them.  

B. They take back some old ones.         

C. They donate them to some charities.  

小题3:According to some countries’ laws, what must computer companies do?  

A. Collect and recycle most of computer waste.   

B. Repair and upgrade old computers.        

C. Make much cheaper computers.  

小题4: What may people who can’t afford computers think of the used computers?  

A. Expensive.        B. Useful.         C. Out-of -date.  

小题5: What is the passage about?  

A. Repairing old computers.  

B. Selling old computers.                

C. Recycling old computers.  

单项选择题