新建矿井、生产矿井新掘运输巷的一侧，管线吊挂高度不得低于（）。
A.1.6m
B.1.7m
C.1.8m
D.1.9m
参考答案：C
—Hi, Helen. You look tired. What happened?
—I ________ well last night. [ ]
A. didn't sleep
B. hadn't slept
C. don't sleep
D. haven't slept
正常生产中，停用压力一次仪表时，如何操作？
