单项选择题
A.fuel supply valve should be closed
B.hatches，doors，and oar ports should be closed
C.air cylinder shut-off valve should be closed
D.engine should be shut off
单项选择题 When launching an open lifeboat by falls，the boathooks should be（）.
单项选择题 When landing a lifeboat through heavy surf with a strong current running parallel to the beach (from right to left when facing from seaward) the recommended procedure is to（）.
单项选择题 When backing a motor propelled lifeboat (right-hand propeller) with the rudder amidships，the stern will back（）.