| 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= B．U= 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：A
| 完形填空。 | ||||
| What does "getting along with your teacher" mean, anyway? "Getting along" means you and your teacher have a relationship that 1 for both of you, and that you both get what you 2 from the relationship. For your teacher, he or she wants to make 3 you are careful, being respectful and polite, and 4 your best to learn. For you, you 5 a teacher who respects you, answers your questions, and tries to 6 you learn. You can get along with your teacher and learn without being friends with him or her, although it's 7 if that happens. In every school, kids say some teachers are too 8 or serious, but don't judge a teacher 9 you are in his or her class and can see for yourself. Most of time, your teacher is on your 10 . And a teacher who's strict may be someone who 11 to do his or her job well-teaching you the 12 you should learn. It's also 13 to remember that making mistakes is a 14 of learning. By pointing out your mistakes and helping you 15 them, a teacher is teaching you. | ||||
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