单项选择题
A.black B.setting C.being D.having
The tide（）.It’s 2 hours before low water，and（）your pres...
单项选择题The tide（）.It’s 2 hours before low water，and（）your present position you will be aground at low water.
A.falls／in B.has been falling／on C.has fallen／at D.is falling／in
The term flood current refers to that time when the wat...
单项选择题The term flood current refers to that time when the water（）.
A.is flowing towards the land B.is moving towards the ocean C.level is not changing D.level is rising because of heavy rains
The steady current circling the globe at about 60°S is ...
单项选择题The steady current circling the globe at about 60°S is the（）.
A.Prevailing Westerly B.Sub-Polar Flow C.West Wind Drift D.Humboldt Current
