单项选择题
An oxygen indicator will detect （）.
A.the amount of oxygen in a space B.the presence of harmful amounts of carbon monoxide C.concentrations of explosive gas D.All of the above
单项选择题 When making entries in the Oil Record Book, all quantifies should be（）.
单项选择题 When fighting a spreading fire resulting from a broken fuel line, you should FIRST （）.
单项选择题 The three basic elements necessary for any fire are （）.
