题目

按要求完成下列各题 1. Can Betty and Tony play basketball?(作否定回答)                                 2. Is there a pen in your bag? (作肯定回答)                                  3. There are some pictures on the wall(墙). (改为否定句)                               4. There is an eraser under the desk.(改为一般疑问句)                                5. There are fifty–two books on the desk.(对划线部分提问)           如图所示，是一条与轴重合的电场线上各点的电势φ随x变化的图线．若在点由静止释放一个点电荷，点电荷仅受电场力作用．取处的电势为零，电荷运动的过程中，下列说法中正确的是(     )A．电荷一定沿x轴正方向运动B．电场力一定做正功C．电荷的电势能可能为正D．电荷受到的电场力逐渐减弱