问题 多选题

如图所示,变压器右端线圈连接的平行金属导轨置于匀强磁场中,金属棒L在导轨上以OO′为平衡位置作简谐振动,其中CC′,DD′为运动的最大位移处.那么,当金属棒L处于下述哪一位置时,通过电流表的电流有最大值(  )

A.CC′

B.OO′

C.DD′

D.不在上述位置

答案

金属棒在磁场中做简谐运动,由于棒的切割运动,产生感应电动势,出现感应电流,当速度最大时产生电动势也最大,当位移最大时棒速度为零,棒刚好没有感应电流,则线圈H中磁通量的变化率最大,所以感应电流也是达到最大,做简谐运动的物体在位移最大时的速度为零.

故选:AC

阅读理解

任务型阅读。

      Now the idea of  "car sharing" has become popular in Europe and the United States. That's to say,

 people share (分享) one car, not each person has one . (1) As we know, most cars are parked in

 garages for much time. In fact, we drive our own cars as long as one or two hours a day on average.

 When we don't use them, We have to pay for parking and other things. (2) We spend too much money

  on that. If we share a car, we'll only pay when we use it. (3) Because some people want to save

 money, they come up with the idea of 'car sharing'. Now many people are starting to do car sharing.

 In Switzerland, almost 40,000 people have joined it. Japan is also trying to make "car sharing" popular

 around the country. (4) car, is, of, new, sharing, transportation, beginning, a, idea, the, in . (5) This is 

  also very easy for us to travel here and there without buying cars. Do you love to share a car with

 others?

任务1:请将(1)处的句子翻译成汉语。

1. ________________________________________

任务2:在下面的空白处填上一个适当的单词,使句意与(2)处相同。

2. That _____ us too much money.

任务3:对(3)处的划线部分提问。

3. ________________________________________?

任务4:请将(4)处的单词组合成一个完整的句子。

4. ________________________________________

任务5:(5)处有一处错误,请找出错误并改在下面的横线上。(可用文字叙述)

5. ________________________________________

单项选择题