Prior to reading an aneroid barometer，you should tap the face lightly with your finger to（）.

单项选择题Pressure gradient is a measure of（）.

A.a high-pressure area
B.pressure difference over horizontal distance
C.pressure difference over time
D.vertical pressure variation

单项选择题On what does the operation of an aneroid barometer depend?（）

A.Thin，metal，air tight cell
B.Curved tube containing alcohol
C.Column of mercury supported by atmospheric pressure
D.Expansion of mercury in a closed tube

单项选择题MODERATE WAVES，TAKING A MORE PRONOUNCED LONG FORM；MANY WHITE HORSES ARE FORMED.THIS sea condition is likely to be termed（）.

A.moderate breeze
B.fresh breeze
C.strong breeze
D.near gale

单项选择题In the Northern Hemisphere，winds veering sharply to the west or northwest with increasing speed are indications that a（）.

A.cold front has passed
B.low pressure center is approaching
C.stationary front exists
D.high pressure center has passed

单项选择题In the Northern Hemisphere，what type of cloud formations would you expect to see to the west of an approaching tropical wave?（）.

A.Cumulus clouds lined up in rows extending in a northeast to southwest direction
B.High altostratus clouds in the morning hours
C.Cirrostratus clouds lined up in rows extending in a northeast to southwest direction
D.Cirrostratus clouds lined up in rows extending in a north to south direction