99色精品-9色在线-99色在线-99色视频 国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

單項(xiàng)選擇題

An air compressor can be unloaded at start-up by ().

A.holding the discharge valve open
B.relieving the intercooler pressure to the atmosphere
C.using an enlarged, permanently opened clearance expansion space
D.a pre-charged accumulator

微信掃碼免費(fèi)搜題