问题 选择题

如图,两根相互平行的长直导线分别通有方向相反的电流,且;a、b、c、d为导线某一横截面所在平面内的四点,且a、b、c与两导线共面;b点在两导线之间,b、d的连线与导线所在平面垂直。磁感应强度可能为零的点是

[ ]

A.a点    

B.b点    

C.c点      

D.d点  

答案

答案:C

综合

读图及下表,回答下列问题:

地点
海拔高度(米)17143760.858.9
年均温(度)36-2.222.321.8
年均降水量(mm)610.8339.82047.51680

(1)说明①、④两地年均温和年降水量差异的原因。                                                                                                                                                                                                                                                                                                                              (2)分析①地降水量高于②地原因。                                                                                                                                                              (3)分析③和④地年均温接近但降水量差异较大的原因。                                                                                                                                                              

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