单项选择题
A.concentrations of explosive gas
B.an oxygen deficiency in a space
C.the presence of harmful amounts of carbon monoxide
D.All of the above
单项选择题 The term "oily mixture", as defined in the Pollution Prevention Regulations includes （）.
单项选择题 The term "oil", as used in the Pollution Prevention Regulations, means （）.
单项选择题 Which of the actions listed should be taken by the engineer on watch when the general alarm is sounded continuously for 10 seconds?（）