单项选择题
A number of biological sewage treatments plants are in use at sea but nearly all work on the principle called （）
A.deoxygenating B.extended aeration C.oxygenating D.bubbling air
单项选择题 Which of the following would not be burnt in an incinerator on board?（）
单项选择题 During waste clothes being charged into an incinerator, the auxiliary burner（）.
单项选择题 The solid waste was charged into the incinerator through （）.
