电除尘器运行中,人孔门必须安全联锁的原因是什么?
参考答案:
电除尘器运行中处于负压状态,若当人孔门开着时,人接近人孔门有可能会被吸入电场内造成损伤,甚至高压电击事故。
呕吐伴腹泻 ()
A.急性肠炎
B.晕车
C.胆石症
D.脑炎
E.急性下壁心肌梗死
----Does Liu Hua serve in the army?
----No,but he ___in the army for three years.
A.served
B.has served
C.is serving
D.would serve