单项选择题
A.The higher high waters B.The lower high waters C.The lower of the two daily tides D.All high waters
Mariners not entering the port are（）to keep at least on...
单项选择题Mariners not entering the port are（）to keep at least one mile off.
A.Advised B.Reported C.Complied D.Supplied
Many of the lights on this coast are placed so high as ...
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
Lines drawn through points on the Earth having the same...
单项选择题Lines drawn through points on the Earth having the same atmospheric pressure are known as （）.
A.Isothermal B.Millibars C.Isobars D.Seismics
