开启气体钢瓶的操作顺序是: ( ) (1) 顺时针旋紧减压器旋杆; (2) 反时针旋松减压旋杆;(3) 观测低压表读数;(4) 观测高压表读数; (5) 开启高压气阀
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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