单项选择题
A.changing pump discharge pressure in response to normal load variations
B.a high oil level
C.incorrect fluid viscosity
D.continued slow re-circulation of the oil
单项选择题 The purpose of the low pressure cut-out switch is to （）.
单项选择题 The process of boiling seawater in order to separate it into freshwater vapor and brine is usually defined as （）.
单项选择题 In the production of freshwater from seawater through a process of heating and cooling, the cooling phase of production is usually called （）.