单项选择题
As compared to carbon dioxide，dry chemical has which advantage?（）.
A.Cleaner B.Effective on metal fires C.Greater range D.More cooling effect
单项选择题 As an extinguishing agent，foam（）.
单项选择题 Any ship damaging a pipe could（）an immediate danger of fire.
单项选择题 Any firefighting equipment that is carried in addition to the minimum required must（）.
