单项选择题
Many of the lights on this coast are placed so high as to be frequently obscured by（）.
A.Power B.Tower C.Cover D.Shower
单项选择题 Lines drawn through points on the Earth having the same atmospheric pressure are known as （）.
单项选择题 Light Lists for coastal waters are（）.
单项选择题 Important changes to charts and lights（including temporary ones），radio signals and sailing directions are listed in（）.
