问题 选择题
如图所示为一磁流体发电机示意图,A、B是平行正对的金属板,等离子体(电离的气体,由自由电子和阳离子构成,整体呈电中性)从左侧进入,在t时间内有n个自由电子落在B板上,则关于R中的电流大小及方向判断正确的是(  )

A.I= ,从上向下

B.I= ,从上向下

C.I= ,从下向上

D.I= ,从下向上

答案

答案:A

选择题
完形填空

Mr Smith was a wealthy industrialist, but he was not satisfied with life. He did not sleep well and his food did not  21  with him. The situation lasted for some time. Finally, after a   22  of sleepless nights, he decided to consult his doctor. The doctor advised a change of  23 . “Go abroad,” he said, “But I’m not good at foreign languages,” said Mr Smith. “It doesn’t matter,” said the doctor. “It won’t   24  you to talk a little less. Go on a voyage. Take plenty of exercise. Try to reduce your weight,  25  rich food.”

Mr Smith went to Switzerland. He did not know French or German, and had to communicate through gestures. He attended a physical training course. The instructor made him bend his knees, swing his arms, stretch his neck and shake his head rapidly. He had to lie on the ground and raise his right and left legs   26  . After a time his muscles grew hard and firm. The life suited him; he almost put aside his financial  27  and nearly forgot the importance of making more money. He even began to  28  individual trees and individual birds. He ate and slept well. Finally he returned home. But unfortunately his improvement was temporary. Soon he was a   29  businessman again, worried about his property, his profits, his savings, his success in a  30  society, and things in general.

21. A. agree                 B. taste                 C. suit                  D. fit

22. A. series                 B. course              C. number            D. few

23. A. situations           B. surroundings      C. weather            D. life

24. A. stop                   B. hurt                 C. help                 D. prevent

25. A. eat                           B. prepare            C. avoid               D. try

26. A. highly               B. widely                    C. alternately        D. regularly

27. A. hardship            B. debts                C. worries            D. success

28. A. see                           B. notice               C. glance               D. consider

29. A. rich                   B. happy               C. normal                    D. successful

30. A. struggle                    B. business           C. miserable         D. competitive