Which of the following statements describes the functions of a reservoir used in a hydraulic system?（）

A.Dissipate heat
B.Trap foreign matter
C.Separate air from the oil
D.All of the above

A.Proper refrigerant charge
B.Faulty expansion valve
C.Insufficient refrigerant
D.Solenoid valve stuck open

A.freezing the expansion valve closed
B.corrosion of system piping
C.improper temperature regulation
D.all of the above