单项选择题
A.flow of oil B.pressure of oil C.A and B D.temperature of oil
（） are used to limit the pressure in any particular por...
单项选择题（） are used to limit the pressure in any particular portion and mainly control the pressure after the valve.
A.Relief valves B.Check valves C.Safety valves D.Reducing valve
Among the basic categories of equipment, which of the f...
单项选择题Among the basic categories of equipment, which of the following is used to convert hydraulic energy into continuous rotary motion?（）
A.Hydraulic pumps B.Valve C.Hydraulic cylinders D.Hydraulic motors
单项选择题Among the basic categories of equipment, which of the following are used to convert mechanical into hydraulic energy?（）
A.The hydraulic pumps B.Valves C.Hydraulic cylinders D.Hydraulic motors
