单项选择题 Before marine sewage treatment plant works （） should be filled with fresh water.

单项选择题 When does auxiliary burner of rotary nozzle incinerator begin to work? （） Ⅰ.hen igniting Ⅱ.he sludge for dealing with is too much Ⅲ.efore stopping incinerator

单项选择题 When the incinerator is stopped, which of the following is wrong?（）