问题 选择题
如图所示,两根相距为l的平行直导轨ab、cd、b、d间连有一固定电阻R,导轨电阻可忽略不计;MN为放在ab和cd上的一导体杆,与ab垂直,其电阻也为R;整个装置处于匀强磁场中,磁感应强度的大小为B,磁场方向垂直于导轨所在平面(指向图中纸面内);现对MN施力使它沿导轨方向以速度v(如图)做匀速运动;令U表示MN两端电压的大小,则(  )

A.U=vBl,流过固定电阻R的感应电流由b到d

B.U=vBl,流过固定电阻R的感应电流由d到b

C.U=vBl,流过固定电阻R的感应电流由b到d

D.U=vBl,流过固定电阻R的感应电流由d到b

答案

答案:A

阅读理解

根据短文内容,从短文后的七个选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

As we “happen to be” the best creature in the world, it’s our duty to look after other species. Here are some points which might help to protect wildlife. Join organizations like Greenpeace and World Wildlife Fund. They have devoted themselves to protecting the earth and its animals. Many volunteers join organizations like these and work for the environment. 小题1:

小题2:  Don’t buy something made from ivory and things like this. Baby seals(海豹) are hunted for their skin, as it is used to make expensive coats. Don’t buy them.

小题3:  You can write a heartfelt and logical letter to the government stating your ideas about this problem and how it can be solved.

Recycle(回收利用) and reuse. It will reduce the need to have more raw materials to produce something.小题4:And wild animals’ home will not be destroyed.

Governments should create more safe zones and national parks for wild animals.  小题5: Governments should apply strict laws to stop hunting.

I hope this post was helpful. Share your views about this issue and let your voice be heard.

A.Let your voice be heard.

B.Stop hunting for pleasure.

C.As a result, fewer trees will be cut down.

D.You can build a bird house and feed local birds.E.Refuse fur coats and medicines made from rare animals

F.You can find some organizations like these and join them.

G. There they will be able to move freely without worrying about hunters.

选择题