矿井（）制定主要通风机停止运转的应急预案。
A.应当
B.必须
C.允许
参考答案：B
How _____ I was when I heard the ______ news!
A．disappointing; disappointed
B．disappointed; disappointing
C．disappointing; disappointing
D．disappointed; disappointed
聪聪晚上10时睡觉，第二天早上6时起床，她一共睡了______小时．
