in an area of high density the water's surface is lower than in an area of low density
surface water flows from an area of high density to one of low density
the lesser the density gradient the freer the water is to move
it is the density differences that cause the currents to stay in the troughs
第1题：
I don-t think differences are important in __a___________（友谊）
第2题：
A、most common
B、commonest
C、commoner
D、the common
第3题：
Control chart theory is based on the differentiation of the causes of variations in quality. Variations may be produced by assignable causes. All of the following are examples of assignable causes except:
A . differences among machines.
B . differences among workers.
C . differences among materials.
D . differences in each of these factors over time.
E . None of the above (all are examples)
第4题：
第5题：
Gradient currents caused indirectly ______．
A.by the wind
B.by the wind or by density differences in adjacent areas
C.Coriolis force
D.by ships sailing in the oceans
第6题：
There are one or two minor differences, but they are ________ the same text.
A substantially
B exceedingly
C remarkably
D separately
第7题：
When is the density of the water required to be logged in the logbook of a ship?
A.Any time the vessel moves from water of one density into waters of a different density
B.Prior to getting underway when the vessel is floating in fresh or brackish water
C.Only when the vessel moves from fresh water into salt water
D.The density of the water is not required to be logged in the unofficial logbook
第8题：
195 Control chart theory is based on the differentiation of the causes of variations in quality. Variations may be produced by assignable causes. All of the following are examples of assignable causes except:
A. differences among machines.
B. differences among workers.
C. differences among materials.
D. differences in each of these factors over time.
E. None of the above (all are examples)
第9题：
The surface currents of the South Atlantic，South Pacific and South Indian Ocean follow，in general，a regular pattern of ______．
A.counter-clockwise circulation
B.clockwise circulation
C.trend from east to west
D.trend from north to south
第10题：