— The government requires that every primary school student do sports for at least one hour every day.

— _____. It is high time that students took exercise in order to build a strong body.

A．That’s what I don’t agree with

B．That’s not the point

C．No wonder

D．I can’t agree more

A、B两个点电荷在真空中所产生电场的电场线（方向未标出）如图所示．图中C点为两点电荷连线的中点，MN为两点电荷连线的中垂线，D为中垂线上的一点，电场线的分布关于MN左右对称．则下列说法中正确的是（　　）

A．这两点电荷一定是等量异种电荷

B．这两点电荷一定等量同种电荷

C．D、C两点的电势一定相等

D．C点的电场强度比D点的电场强度大