单项选择题
After fitting back in place the gear wheels, don’t forget to （） them.
A.fulfill B.eliminate C.grease D.bend
单项选择题 What separate the high pressure side from the low pressure side in a refrigeration system?（）
单项选择题 Which of the following best describes “overcharge of refrigerant”?（）
单项选择题 The presence of air in the condenser of a refrigeration system will （） the condensing pressure.
