单项选择题
Define the acronym MSI（）.
A.Maritime Safety Information B.Maritime Shipping Index C.Maritime Satellite Indicator D.Mariner Safety Intelligence
单项选择题 Deficient oxygen content inside a chain locker can be detected with（）.
单项选择题 Deck beams on a ship are generally spaced at equal intervals and run（）.
单项选择题 Day-shapes must be displayed（）.
