如图所示，在正电荷Q产生的电场中有A、B、C三点（C点未画出），其中A、B两点间的电势差为U_AB=1.5×10³V．现将电荷量q=6×10^-8C的带正电的试探电荷从A点移到B点，电场力做的功是多少？若将该试探电荷再从B移动到C，电场力做的功W_BC=-3×10^-5J，则A、C两点间的电势差是多少？

The old couple, ____had been admitted to university, were living a hard life.

A．both their children

B．both of whom children

C．both of whose children

D．whose their children