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

單項選擇題

When a flash-type evaporator is to be secured for an extended period of time, the entire unit should be drained, cleaned, and ().

A.completely filled with saltwater
B.filled with de-scaling compound
C.tightly closed to exclude air
D.vented to the atmosphere

微信掃碼免費搜題