题目

The pilot asked all the passengers on board to remain (seat) as the plane was making a landing. 答案：【1】seated如图，A、B、C、D是正四面体的四个顶点，现在A固定一电荷量为+q的点电荷，在B固定一电荷量为-q的点电荷，取无穷远电势为零，下列说法正确的是A. 棱AB中点的电势为零B. 棱AB中点的场强为零C. C、D两点的电势相等D. C、D两点的场强相同