单项选择题
By day，you sight a vessel displaying three shapes in a vertical line. The top and bottom shapes are balls，and the middle shape is a diamond. It could be a（）.
A.vessel trolling B.mineclearing vessel C.trawler D.vessel engaged in replenishment at sea
单项选择题 As a rule，ships of most configurations，when drifting in calm water with neglible current，will lie（）.
单项选择题 An inclined semisubmersible with a very short rolling period about a constant angle of list is likely to have（）.
单项选择题 All of the following are engaged in fishing EXCEPT（）.
