单项选择题
A.Carbon dioxide B.Carbon monoxide C.Carbon trioxide D.Hydrogen sulfide
Seawater may be used for drinking water （）.A.at a maxim...
单项选择题Seawater may be used for drinking water （）.
A.at a maximum rate of two ounces per day B.after mixing with an equal quantity of fresh water C.if gather during or immediately after a hard rain D.under no circumstance
A class "D" fire would be considered as burning （）.A.wo...
单项选择题A class "D" fire would be considered as burning （）.
A.wood B.oil C.electrical equipment D.magnesium
One of the methods NOT usually allowed in cleaning up o...
单项选择题One of the methods NOT usually allowed in cleaning up oil spills in the United States is （）.
A.skimmers B.straw C.dispersants D.sawdust
