单项选择题
A.repack all valve stems B.lubricate it prior to use C.replace the foundation bolts D.balance the warping heads
The color of the flame on a halide torch without any re...
单项选择题The color of the flame on a halide torch without any refrigerant present is （）.
A.blue B.green C.orange D.purple
If a refrigeration compressor is running continuously w...
单项选择题If a refrigeration compressor is running continuously without lowering temperature as normal in the refrigerator, the trouble may be （）.
A.excessive condenser cooling water B.warm food in the refrigerator C.a shortage of refrigerant D.s shortage of compressor oil
