单项选择题
When reentering an engine room that has been flooded with CO2, the investigating team should initially（）.
A.leave the access door partially open B.enter from the lowest level C.enter from the highest level D.attempt to operate machinery
单项选择题 If there has been a fire in a closed unventilated compartment it may be unsafe to enter because of （）.
单项选择题 After a fire has been extinguished in a closed space, personnel may safely enter the space when （）.
单项选择题 Which of the petroleum products listed has the lowest flash point?（）
