三个电子各具有与磁场方向垂直的速度v、2v、3v，则它们在同一匀强磁场中回旋的半径之比和频率之比为[ ]

A．1∶2∶3，1∶2∶3

B．1∶2∶3，1∶1∶1

C．1∶1∶1，1∶2∶3

D．1∶1∶1，1∶1∶1

I knew nothing of the motives behind his recent move, and I don't know either the person to put him up to the action.

A．nor did I know ... who

B．not did I know ... that

C．nor do I know ... that

D．either did I know ... who