单项选择题
A.temperature of the air equals the temperature of the seawater
B.atmospheric pressure is 14.7 lbs. per square inch
C.relative humidity reaches 50%
D.air becomes saturated with water vapor
单项选择题 The design specifications for cranes and crane foundations on ship’s are set and published by the（）.
单项选择题 The depth（）a shallow patch，lying about 1.3 miles southeastward of Nanshan Tou lighthouse reduces to about 6.1 meters.
单项选择题 The datum from which the predicted heights of tides are reckoned in the tide tables is（）.