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

Any extinguishing agent used on a Class “C” fire must have which important property? ()

A.Cooling ability
B.Leaves no residue
C.Penetrating power
D.Nonconductivity

微信掃碼免費(fèi)搜題