将一个平行板电容器接上电源后再切断电源，然后使两极板间的距离增大一些，则关于电容器两极的电压U和两极间的场强E的变化，下列说法正确的是 [ ]

A.U增大，E增大

B.U增大，E不变

C.U不变，E减小

D.U减小，E减小

All the people in the nation can remember exactly how many years ago _______ the civil war broke out.

A．was it that

B．it was when

C．it was that

D．was it when