单项选择题
A.flammable vapor by volume in air
B.oxygen present to support combustion
C.the temperature of the flash point
D.the lower limit of explosibility of the mixture
单项选择题 What safety precautions should be observed by the crew while working around machinery in an engine room?（）
单项选择题 The word "discharge" as used in Pollution Prevention Regulations applies to oil （）.
单项选择题 If fuel tank levels are found to have increased after a grounding, you should suspect （）.