题目

两根通电的长直导线平行放置,电流分别为和,电流的方向如图4所示,在与导线垂直的平面上有、、、四点,其中、在导线横截面连线的延长线上, 、在导线横截面连线的垂直平分线上.则导体中的电流在这四点产生的磁场的磁感应强度可能为零的是 图4A. 点                                                                                                                             B. 点C. A lot of trees are_______of the street and the number of them is growing_______.A.on both side,greaterB.on both sides,largerC.on each side,moreD.every side,more