启动预研磨器前，不必保证（）。
A、预研磨器内有物料
B、预研磨器内无杂物
C、预研磨器门关好
D、预研磨器的安全联锁无报警
参考答案：A
—Why were you late for the party?
—I ______ in the heavy traffic.Otherwise I ______ earlier.
A．got stuck；came
B．got stuck；would have come
C．have got stuck；would have come
D．got stuck；would come
动脉导管结扎术易并发
A．Ⅲ度房室传导阻滞
B．肺动脉瓣返流
C．喉返神经损伤
D．膈神经损伤
E．三尖瓣返流
