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先化简后求值:(x-y)(y-x)-[x2-2x(x+y)],其中x=12,y=

题型:解答题

题目:

先化简后求值:(x-y)(y-x)-[x2-2x(x+y)],其中x=
1
2
,y=-2

答案:

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题型:阅读理解

阅读理解

     There is a growing problem of what to do with electronic waste such as old televisions, computers,

radios, cellular telephones and other electronic equipment.

     Electronic trash, or e-waste, is piling up faster than ever in American homes and businesses. People

do not know what to do with old televisions or computers so they throw them in the trash.

     National Solid Wastes Management Association(NSWMA) state programs director Chaz Miller says

the large amount of electronic waste Americans produce is not unexpected.

    The US Environmental Protection Agency (EPA) estimates more than 400 million consumer electronic

items are dumped each year, and there is a push by more states to ban the waste from landfills(垃圾填

埋场) and create recycling programs. They can be torn apart and sorted for useable parts. Mike Fannon who runs the plant in Baltimore, says, "There are a lot of valuable metals that can be recovered and

reused instead of just putting them in the landfill, and in certain components there are some materials that

should not really be in the landfill," Fannon explained.

    Fannon says nearly 20 percent of electronic waste is recycled nationwide. Thirteen years ago, it was

only about 6 percent. Recycling rates continue to rise as more communities have banned electronics from

landfills in an effort to keep e-waste poisons like lead(铅) and mercury(汞) out of garbage dumps.

    This year several states like Vermont imposed a ban on electronic waste in landfills. More than 25

other states have also adopted landfill bans, e-waste recycling programs or both. Chaz Miller says more

can be done to boost electronic waste recycling.

     "We can do much better," noted Miller. "I think clearly our goal should be to do as well as we do

recycling newspapers."

1. Which of the following does NOT belong to e-waste? 

A. Old televisions.

B. Old computers.

C. Old cell phones  

D. Old newspapers.

2. Why is e-waste banned from landfills in many states? 

A. Because it can not be recycled. 

B. Because it might damage the environment. 

C. Because it can be shipped to other countries. 

D. Because the landfills are already full.

3. According to Mike Fannon, what might be the best way of dealing with e-waste? 

A. Recycling it.

B. Selling it. 

C. Burying it.

D. Breaking it.

4. What can we learn from the passage?   

A. At present, less then 10 percent of e-waste is recycled. 

B. Chaz Miller works for EPA. 

C. All states in the US have banned e-waste from landfills. 

D. Experts are optimistic about the future of e-waste.

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