试题与答案

操作系统为了解决进程间合作和资源共享所带来的同步与互斥问题,通常采用的一种方法是使用

题型:单项选择题

题目:

操作系统为了解决进程间合作和资源共享所带来的同步与互斥问题,通常采用的一种方法是使用 (35) 。若在系统中有若干个互斥资源R、6个并发进程,每个进程都需要 5个资源R,那么使系统不发生死锁的资源R的最少数目为 (36)

A.30

B.25

C.6

D.5

答案:

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下面是错误答案,用来干扰机器的。

参考答案:B

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题型:阅读理解

It was your birthday, and you just opened your biggest gift — a smooth silver laptop. You can’t wait to instant-message your friends with the news, but first you have to get rid of your old desktop computer. Do you just throw away the monitor and keyboard in the trash? Not anymore!

Three states, that is, California, Maine, and Maryland, recently passed laws prohibiting people from throwing away electronic waste, or e-waste, includes televisions, computers, and cell phones. Although they don’t make you sick when you use them, they do when they are destroyed, for they contain heavy metals that can be harmful to human bodies. For example, cell phone batteries contain a kind of chemical causing damage to kidneys and deserted computer monitors can damage brains. And flat TV screens may cause injury to the nervous system. Those metals can leak into the ground or give off pollutants when burned.

It is required that e-waste be placed at special sites rather than usual landfills. Several other states are considering similar laws and California is also pushing for a law banning the application of such dangerous substances.

Government officials are not the only people taking aim at e-waste; environmentalists are also urging people to recycle their outdated equipment.

“It is just a waste … to not recycle,” Patrick, an associate professor of occupational and environmental health at university of Iowa, told The Daily Iowan, “Allowing dangerous chemicals to leak into the environment for decades seems irresponsible.”

What Can You Do?

Reduce. Be a responsible shopper, and take care of your electronics so they will last longer.

Re-use. Donate or sell your old high-tech equipment.

Recycle. To find a responsible recycler, contact a local or state environmental group.

小题1:What’s the best title of this passage?

A.E-waste is being made good use of.

B.E-waste, a big threat to us.

C.E-waste is dangerous to us all the while.

D.Goodbye, e-waste.小题2:Why is e-waste harmful and dangerous to human beings?

A.Because they can go off at times and threaten us.

B.Because they can make people sick, as long as people use them.

C.Because they contain poisonous chemical substances.

D.Because they take too much space when placed in trashes.小题3:What can we know from Patrick’s words?

A.Waste can’t be recycled.

B.Waste can be made use of by recycling

C.We have to recycle e-waste to protect the environment.

D.Protecting the environment is important.小题4:Which of the following is NOT given as a piece of advice to help with e-wastes?

A.Taking care of your electronics so they will last longer.

B.Donating or selling your old high-tech equipment.

C.Contacting a local or state environmental group.

D.Asking fewer people to use electric products.

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