______ is a low，even layer of dark grey clouds，with light and dark patches.A.CirrostratusB

In an alternating current electrical system, a low system power factor is a direct sign of _____.

The purpose of the low pressure cut－out switch is to _____.A.maintain liquid refrigerant a

The most common source of excitation for synchronous motors is a／an _____.A.low voltage ba

Sea water is not used directly as a coolant because of _____.A.low specific heatB.high spe

The function of lubricating oil is to ______.A.maintain even distribution of bearing wearB

Either a low injection pressure or a leakage of piston rings is able to lead _____.A.a hig