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

单项选择题 A1/A2型题
填空题



Every human being is fallible; we make mistakes. In America when a mistake has been made, it is considered fitting for the person (1) to acknowledge his or her error and to apologize to anyone who has been inconvenienced. Even (2) are expected to admit their mistakes and apologize for them. Trying to (3) a mistake and denying your guilt are considered to be indicative of serious (4) .
If you make a mistake that (5) a group of people, a public apology is considered the best method for (6) . If the mistake was a serious one, or if some people were inconvenienced more than others, then the (7) should follow the public apology with private ones to (8) .
It is especially important for executives and company heads to be able to admit their mistakes. Sometimes leaders are afraid that if they (9) , they will lose the respect of their employees. Actually (10) — if you are honest with your employees and yourself, (11) , and show that you are willing to accept blame when you make a mistake, then your employees will be (12) you. They will also be more likely to admit their own mistakes.
If you (13) one person, it is usually best to apologize to that person alone, unless your mistake (14) by a large group of people. For example, if Leonard (15) to Mr. Todd during a committee meeting, it would be (16) for Leonard to apologize to Mr. Todd at the next committee meeting. If the (17) created by the initial mistake is public, then the apology should be public. However, if Leonard raised his voice to Mr. Todd when only the two of them (18) , he may apologize privately. Notice as well (19) the apologies are. As soon as you realize you have made a mistake, you should (20) .