如图所示，质量为为m、电量为q的带电粒子，经电压为U加速，又经磁感应强度为B的匀强磁场后落到图中D点，求A、D间的距离和粒子在磁场中运动的时间。

All the parents in Mianyang admire Nanshan Middle School         the teachers are treating their students like friends.

A．why

B．where

C．that

D．which