无码高清视频|成人自拍视频|欧美成人午夜无码A片秀色直播|草美女视频网站|美女被操网站在线观看

單項(xiàng)選擇題

When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be ().

A.dehydrated
B.purged
C.plugged
D.evacuated

微信掃碼免費(fèi)搜題