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（）.
A.air gap B.freeboard C.penetration D.water depth
单项选择题 The distance between the surface of the water and the tidal datum is the （）.
单项选择题 The distance between any two meridians measured along a parallel of latitude and expressed in miles is the （）.
单项选择题 The distance between any two meridians measured along a parallel of latitude （）.
