单项选择题
A.Point the horn down
B.Turn cylinder upside-down
C.Break the rupture disc
D.Pull pin，squeeze grip
单项选择题 How do you determine the weight of the vessel that is supported by the ground when a vessel has run aground?（）
单项选择题 How do the height and location of a tug’s towing bitts relate to the danger of tripping?（）
单项选择题 How could lashing gear used aboard Ro-Ro vessels be stowed when not in use?（）