（）一旦发生事故可能会引起灾难性的后果
参考答案：特种设备
Mr. Green _______ his lessons when I went into his office.
A．prepares
B．prepared
C．is preparing
D．was preparing
导致文学批判运动此起彼伏愈演愈烈的原因的原因是什么？
