GRE考试

【单选题】Ocean water plays an indispensable role in
supporting life. The great ocean basins hold about
300 million cubic miles of water. From this vast
Line amount, about 80,000 cubic miles of water are
(5) sucked into the atmosphere each year by evapora-
tion and returned by precipitation and drainage to
the ocean. More than 24,000 cubic miles of rain
descend annually upon the continents. This vast
amount is required to replenish the lakes and
(10) streams, springs and water tables on which all
flora and fauna are dependent. Thus, the hydro-
sphere permits organic existence.
The hydrosphere has strange characteristics
because water has properties unlike those of any
(15) other liquiD、One anomaly is that water upon
freezing expands by about 9 percent, whereas
most liquids contract on cooling. For this reason,
ice floats on water bodies instead of sinking to the
bottom. If the ice sank, the hydrosphere would
(20) soon be frozen solidly, except for a thin layer of
surface melt water during the summer season.
Thus, all aquatic life would be destroyed and the
interchange of warm and cold currents, which
moderates climate, would be notably absent.
(25)Another outstanding characteristic of water is
that water has a heat capacity which is the highest
of all liquids and solids except ammoniA、This
characteristic enables the oceans to absorb and
store vast quantities of heat, thereby often pre-
(30) venting climatic extremes. In addition, water dis-
solves more substances than any other liquiD、It is
this characteristic which helps make oceans a
great storehouse for minerals which have been
washed down from the continents. In several
(35) areas of the world these minerals are being com-
mercially exploiteD、Solar evaporation of salt is
widely practiced, potash is extracted from the
Dead Sea, and magnesium is produced from sea
water along theAmerican GulfCoast.
According to the passage, fish can survive in the oceans becauseA．they do not need oxygen
B．ice floats
C．evaporation and condensation create a water cycle
D．there are currents in the oceans
E、water absorbs heat

网考网参考答案：B
网考网解析：
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