单项选择题
A.suction pressure regulator
B.thermostatic bypass valve
C.sea water temperature
D.water level in the expansion tank
单项选择题 Mechanical lubricators for diesel engine cylinders are usually small reciprocating pumps which are （）.
单项选择题 Bottom blow valves are installed on auxiliary water-tube boilers to （）
单项选择题 A three-way thermostatic control valve regulates the diesel engine cooling water temperature by passing a portion of the water （）.