单项选择题
Clean oil is achieved in a clarifier bowl where the impurities and water collect at the bowl （）.
A.bottom B.top C.center D.periphery
单项选择题 The fresh water generator produces fresh water （）.
单项选择题 Because of the reduced （） in the vacuum boiling evaporator, some of the sea water boils as it flows through the tubes.
单项选择题 We use （） to distill fresh water from sea water.
