单项选择题
Before starting a reciprocating, steam-driven pump that has been idle for a period of time, you should （）.
A.open the steam line mot valve B.drain the steam cylinder C.close the steam cylinder drains D.open the liquid cylinder drains
单项选择题 When air becomes trapped in the hydraulic fluid of a steering system, the （）.
单项选择题 If a refrigeration system were short of refrigerant, the condition would result in （）.
单项选择题 Condensate must be drained from the intercooler and after-coolers of an air compressor because （）.
