单项选择题 The main tasks for sailors on duty are, first of all, （）persons who come on board to do their business, such as the PSC inspectors, the agent, the ship chandler, etc.

单项选择题 When a vessel is alongside the wharf, it’s necessary for the ship to keep a （）hour gangway watch to guarantee the safety of the ship and the cargo.

单项选择题 The head line is （）(松弛的).