(2) The method of collecting gas sample Z in the mine is to bring Z gas cylinder filled with water into the mine, pour out the water and cover it with glass. So fill in: bring the Z cylinder full of water into the mine, pour out the water and cover it with glass.
(3) Turn on the light, turn on the exhaust fan or range hood, and explosion may occur; The correct Z method should be to close the valve and open the doors and windows.