单项选择题
A.the pressure regulating valve is not closing B.an excessive lack of refrigerant in the system C.badly leaking discharge valves D.worn piston rings
Which of the following statements describes the relatio...
单项选择题Which of the following statements describes the relationship between flash point and ignition temperature?（）
A.Both are higher than normal burning temperatures B.The flash point is always higher C.The ignition temperature is always higher D.They are not necessarily related
Flexible hose under pressure in a hydraulic system will...
单项选择题Flexible hose under pressure in a hydraulic system will （）.
A.tend to twist about its long axis B.expand in length and in diameter C.contract in length and expand in diameter D.flex at right angles to the applied pressure
An air compressor can be unloaded at start-up by （）.A.h...
单项选择题An air compressor can be unloaded at start-up by （）.
A.holding the discharge valve open B.relieving the intercooler pressure to the atmosphere C.using an enlarged, permanently opened clearance expansion space D.a pre-charged accumulator
