题目

如图所示，A、B是一条电场线上的两点，若在A点释放一初速为零的电子，电子仅受电场力作用，沿电场线从A运动到B．则(     ) A．电场强度的方向向左    B．A点场强一定大于B点场强 C．电场力做负功                   D．电势能增加               答案：A–When _______ you _______ your homework?--I had finished it before he _______ backA. have; finished; came B. have; finished; was comingC. did; finish; came D. did; finish; was coming