单项选择题
All the crew must know the locations as well as the （）of the life-saving and fire-fighting appliances.
A.operate B.operating C.operations D.operated
单项选择题 What kind of （）can be used for gas and chemical fires?
单项选择题 Fires can be divided into different （）.
单项选择题 We are loading dangerous cargo, no （）, please.
