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（）.

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（）.