单项选择题 Vessels lying afloat at buoys for more than 24 hours should use anchor chain for（）and insurance wire for（）.

单项选择题 To ensure the best results during the Mediterranean moor，the chains should（）.

单项选择题 There are two classes of vessels which，to the extent necessary to carry out their work，do not have to comply with the rule regarding traffic separation schemes. One of these is a vessel（）.