一条载流长直导线,在导线上的任何一点,由导线上的电流所产生的磁场强度为零。
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在电子仪器中,为了减弱与电源相连的两条导线所产生的磁场,通常总是把它们扭在一起。
A. 对
B. 错
Thisistheonlyoneofthestudents_____thetruth.
A. thatknows
B. thatknow
C. whoknows
D. whichknows
Doyouknowthegirl_____?
A. whomheoftentalkto
B. towhoheoftentalks
C. tothatheoftentalks
D. heoftentalksto
Therearenochildren_____ovetheirparents.
A. thatdonot
B. whodoesnot
C. that
D. who