Coast Pilots and navigational charts are kept corrected and up-to-date by using the（）.

单项选择题Clouds with the prefix “nimbo” in their name（）.

A.are sheet or layer clouds
B.have undergone great vertical development
C.are middle or high altitude clouds
D.are rain clouds

单项选择题Clouds form（）.

A.as a mass of warm，humid air rises into the atmosphere and cools，condensing moisture into small droplets
B.as winds blow across bodies of water，the sun causes the moisture to be absorbed and move upward forming clouds
C.dry air compresses moisture from the atmosphere into clouds
D.when the relative humidity of the atmosphere is low

单项选择题Clean air standards referred to as “Grade D” apply to compressed air for use in（）.

A.high pressure fluid accumulators
B.driving air-powered plunger pumps
C.filling open-circuit breathing systems
D.bladder-type accumulators

单项选择题Class I and II private aids to navigation in or along navigable waters of the United States are listed in the（）.

A.Sailing Directions
B.Light List
C.List of Private Aids
D.Aids to Navigation Manual

单项选择题Chronometer error may be found by（）.

A.radio time signal
B.comparison with a timepiece of known error
C.applying the prevailing chronometer rate to previous readings
D.All of the above