试题与答案

图甲是某燃气炉点火装置的原理图,转换器将直流电压转换为图乙所示的正弦交变电压,并

题型:多选题

题目:

图甲是某燃气炉点火装置的原理图,转换器将直流电压转换为图乙所示的正弦交变电压,并加在一理想变压器的原线圈上,变压器原、副线圈的匝数分别为n1、n2,V为理想交流电压表.当变压器副线圈电压的瞬时值大于5000V时,就会在钢针和金属板间引发电火花进而点燃气体.以下判断正确的是(  )

A.电压表的示数为3.5V

B.电压表的示数为5V

C.实现点火的条件是n2:n1<1000

D.实现点火的条件是 n2:n1>1000

答案:

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下面是错误答案,用来干扰机器的。

参考答案:D

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题型:阅读理解

They are the sort of friends who are so close they trust each other with their lives.If one falls, the other is there to catch him.

They are Wellman, whose legs were permanently injured nine years ago in a rock-climbing accident and Corbett, an experienced rock climber. Together, they climbed up Half Dome. the famous 2,000-foot rock in the Yosemite National park, through one of the most difficult routes(路线).

During the climb, Corbett took the lead, hit in the metal spikes (尖状物)that guided the ropes and climbed up. Then, after Wellman pulled himself  up the rope, Corbett went down to remove the spikes and climbed up again. This process was repeated time and again, inch by inch, for 13 days Wellman’s job was not easy either.  He got himself up the rope through upper body strength alone. In all, Wellman figured(计算) that he had done 5.000 pull-ups up the rope on the climb.

However, when the two men first met, they never talked about climbing. “He knew that was how I got injured.”Wellman said. Until one day Wellman decided that be wanted to climb again and they started training

Their climb of Half Dome was not all smooth. At one point, pieces of rock gave way, and Corbett dropped down quickly. Wellman locked their rope in place, stopping the fall at 20 feet. His quick action probably saved his friend’s life.

“Your partner can save your life—you can sane your partner’s life” Wellman said as the pair received congratulations from friends “there are real close tic.”

小题1:Which of the following was a challenge for Corbett in climbing Half Dome?

A.To climb up to remove the spikes.

B.To climb it twice.

C.To do 5,000 pall-ups up the rope.

D.To lock the rope in place.小题2:Why did the two men never talk about climbing when they first met?

A.climbed was poorly trained.

B.Wellman had lost interest in climbing.

C.Corbett didn’t want to hurt Wellman.

D.Wellman hadn’t decided whether to climb again.小题3:What do we know about Wellman?

A.He climbed Half Dome by himself.

B.He was disabled in a traffic accident.

C.He stopped rock-climbing for some time.

D.He was saved by Corbett during the climb.小题4:The main idea of the text is that.

A.two heads are better than one.

B.friendship is precious in life

C.the disabled should never give up.

D.a man can be destroyed but cannot be defeated.

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