In reading a weather map，closely spaced pressure gradient lines would indicate（）.

单项选择题In North America the majority of the weather systems move from（）.

A.north to south
B.south to north
C.east to west
D.west to east

单项选择题In bad weather，what length of chain should be used with a single anchor? （）

A.3 times the depth of water
B.6 times the depth of water
C.10 times the depth of water
D.15 times the depth of water

单项选择题In a storm，the leeward lines of a ship’s mooring system will（）.

A.pull the unit in the same direction that the weather is pushing it
B.pull the unit in the opposite direction that the weather is pushing it
C.tend to keep the unit on its original location over the well head
D.affect the unit's draft and inclination as maximum mooring tensions are reached

单项选择题If you are caught in the left semicircle of a tropical storm，in the Southern Hemisphere，you should bring the wind（）.

A.on the starboard quarter，hold course and make as much way as possible
B.2 points on the port quarter，and make as much way as possible
C.on the port bow，and make as much way as possible
D.dead ahead and heave to

单项选择题Hurricane warnings are issued（）when winds of force 12 or above are expected.

A.in all parts of the world
B.in some parts of the world
C.from all corners of the world
D.from every corner of the world