起钻过程，如发现井口液面不降，或钻杆内反喷钻井液，这是井塌的象征，应立即（）。
参考答案：停止起钻
—I saw Mr Smith in the office at ten yesterday morning.
—That's impossible. He __________ an English party with us then.[ ]
A. has
B. had
C. was having
D. has had
关于水量指示器说法错误的是？（）
A.水量指示器用来指示水箱的水量
B.水量指示器由5个灯及一个按钮组成
C.水量指示器是由水量传感器来提供指示
D.要拆下水量传感器可以不拆下水箱
