单项选择题
A.to right the raft if it capsizes
B.to carry the raft around on deck
C.for crewmen to hang on to
D.to hang the raft for drying
单项选择题 Each commercial fishing vessel must have at least one immersion suit，exposure suit，or life preserver for each（）.
单项选择题 Deck foam systems，designed to protect cargo areas on tankers built after January 1，1975，must have a supply of foam-producing material to operate the system at its designed rate of foam production for（）.
单项选择题 Cable tension for catenary calculations is taken at the（）.