信号工误发信号的原因主要是注意力不集中或精神不正常造成的。
参考答案：对
—Excuse me, sir. Could you tell me _____?
—At 2:00 pm. [ ]
A. where the meeting was held
B. when the meeting will begin
C. when did the meeting begin
D. where will the meeting be held
转炉炼钢热效率最高的是（）。
A.单渣法
B.双渣法
C.三渣法
D.双渣留渣法
