The Local Notice to Mariners is usually published（）.

单项选择题The issue of Notices to Mariners of charts and these aids(Radar beacons)may be delayed until such time as they are assessed to be（）.

A.temporary
B.permanent
C.occasional
D.steady

单项选择题The external flotation bladder on an immersion suit should be inflated（）.

A.before you enter the water
B.after you enter the water
C.after one hour in the water
D.after you notice that your suit is losing buoyancy

单项选择题The Experimental Lighthouse-buoy has no navigational significance and may be removed at will.The above sentence means（）.

A.It's of no use for navigation and would be removed with notice
B.It's useful in navigation and may be removed without notice
C.It's helpless in navigation and may be removed without notice
D.It's helpful in navigation and may be removed without notice

单项选择题The effect of wind on exposed areas of the vessel is most noticeable when（）.

A.backing
B.going slow ahead
C.going full ahead
D.turning

单项选择题The diurnal variation of pressure is most noticeable（）.

A.above the polar circles
B.in a low pressure area
C.during periods of low temperatures
D.in the doldrums