为了简化安培的实验，我们可以用如图所示的装置探究影响安培力方向的因素．实验中如果发现导体棒被推出磁铁外，则此时磁铁的磁极和电流方向可能是（ ）
A．磁铁N极在上，电流方向A→B
B．磁铁N极在上，电流方向B→A
C．磁铁S极在上，电流方向B→A
D．以上三种情况都有可能
A、磁铁N极在上，电流方向A→B，由左手定则可知，导体棒受到的安培力向里，不符合题意，故A错误；
B、磁铁N极在上，电流方向B→A，由左手定则可知，导体棒受到的安培力向外，符合题意，故B正确；
C、磁铁S极在上，电流方向B→A，由左手定则可知，导体棒受到的安培力向里，不符合题意，故C错误；
D、由以上分析可知，A、C两种情况是不可能的，故D错误；
故选B．
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| The 28-year-old had spent six years working nights while she gained her university degree during the day. When she finally graduated, she had her eye on a teaching 1 at a nearby primary school. With the help of her friends, she had an interview with the Head. "I noticed a tiny hole in one of my stockings earlier," she 2 . "I thought about changing them, but I knew I'd be late if I did. And by the time I got to the interview, 3 enormous. I walked in apologizing for not 4 ." The would be teacher didn't get the job. In fact one of her friends told her that the 5 only comment was:"If someone doesn't take the time to present her best 6 at an interview, what kind of 7 is she going to be?" First impressions are 8 ones. In other words, if you're viewed positively within the critical (关键的) first four minutes, the person you've met will 9 assume everything you do is positive. Leave the interviewer a bad impression, and often he will assume you have a lot of other unsatisfactory characters. Worse, he or she may not take the time to give you a second 10 . Most employers believe that those who look as if they care about themselves will care more about their jobs. | ||||
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