题目

As far as I'm concerned，there is no point ________with him. He will never change his mind. A．argued  B．arguing C．to argue  D．for arguing 答案：B 考查固定句型。there is no point (in) doing sth意为“做某事没有意义”。一质量为m，带电-Q的点电荷用绝缘细线悬挂，置于电场之中，平衡时与竖直方向成θ角．（1）若电场为水平方向的，求场强．（2）保持θ角不变，求最小的场强．