钻机在井下的钻探过程中，需要停止钻机运转时的操作顺序是：（）。
A、先停电再停水
B、先停水再停电
C、同时停水停电
D、无所谓
参考答案：A
一物体由静止开始沿直线运动，其加速度随时间变化规律如图所示，取开始运动方向为正方向，则物体运动的v-t图象，正确的是（ ）
A．
B．
C．
D．
It was not until the entrance exams were in sight that that I had so many books to cover and so many exercises to finish.
A．I realized
B．did I realize
C．had I realized
D．I had realized
