单项选择题 Pollution regulations require that each scupper in an enclosed deck area have a（）.

单项选择题 Owing to the greater girth of a ship amidships than at the ends，certain strakes are dropped as they approach the bow and stern to reduce the amount of plating at the ends. These strakes are called（）.

单项选择题 One function of a bulwark is to（）.