单项选择题
A.that blows towards the sea at night
B.that blows towards an island during the day
C.caused by cold air descending a coastal incline
D.caused by the distant approach of a hurricane
单项选择题 A millibar is a unit of（）.
单项选择题 A microbarograph is a precision instrument that provides a（）.
单项选择题 A mercurial barometer at sea is subject to rapid variations in height (pumping) due to the pitch and roll of the vessel. To avoid this error，measurements of atmospheric pressure at sea are usually measured with a(n)（）.