临床上最常见的上呼吸道梗阻是（）。
A.喉痉挛
B.喉水肿
C.舌后坠
D.气管导管扭曲
E.气管内痰堵塞
参考答案：C
When the accident happened in the factory , the workers__________ screams of terror.[ ]
A. let out
B. picked out
C. looked out
D. died out
怎样防止带式输送机输送带着火事故？
