单项选择题
The height of a light is measured from which reference plane?（）
A.Mean low water B.Mean high water C.Average water level D.Geographical sea level
单项选择题 The Earth’s irregular heating is caused by （）.
单项选择题 The Earth has the shape of a(n) （）.
单项选择题 The distance from the still water level (corrected for tides and storm surge) to the bottom of the hull of a ship is the（）.
