单项选择题
A vessel must proceed at a safe speed（）.
A.in restricted visibility B.in congested waters C.during darkness D.at all times
单项选择题 A vessel is proceeding from a very cold climate to a warm climate.With a cargo of non-hygroscopic nature，which of the following is correct?（）.
单项选择题 A tug would NOT assist a ship to steer if the tug is made up to the large vessel（）.
单项选择题 A towing vessel is tripped when（）.
