单项选择题 When in operation, it is unavoidable that a small amount of oil （） through leakage, and in order to compensate for these leaks the system is connected to a feed pump.

单项选择题 For a L√Opurifier, if the back pressure of the oil outlet is too high, the interface between oil and water in the bowl will （）.

单项选择题 Which of the following influences the position of the interface between the liquid seal and the oil in a purifier?（）