采掘工作面有H2S或SO2气体出现时，可能是透水前的预兆。
参考答案：对
－It’s time for the weather report. Could I__________ the TV, Dad?
－Go ahead, please. I also want to know about the weather for tomorrow.
A. turn on B. turn off C. turn down
电泵空冷器进出口水门的作用是什么？
