单项选择题 A semisubmersible which will not remain upright and will assume a list either to port or starboard is likely to have（）.

单项选择题 A disk with a horizontal line through its center，equivalent to the summer load line，is called the（）.

单项选择题 A deep draft VLCC (100，000 DWT+) navigating in a narrow channel or canal（）.