单项选择题
A.the top 2-1/2 inches of each side
B.the releasing gear lever
C.the fuel tanks
D.the thwarts
单项选择题 In order for combustion to occur inside a piping system such as a vapor collection header in a marine emmission control system，there must be（）.
单项选择题 If the survival craft is not loaded to full capacity，the personnel should be（）.
单项选择题 If help has not arrived in 10-12 hours after you abandon a vessel in a survival craft，you should（）.