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【单选题】
设{ }为等差数列，公差d = -2， 为其前n项和.若 ，则 =A.
18
B.
20
C.
22
D.
24
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【简答题】What is said about the rainfall in America’s West? A) There is much more rainfall in California than in Utah. B) The water it delivers becomes lighter when it moves inland. C) Its chemical composition...
【单选题】Why is it more likely for some families to produce fraternal(异卵双生)twins?
A.
There is a tradition in the family.
B.
There is a secret diet in the family.
C.
There is a hereditary tendency in the family.
D.
There is a special way in the family.
【简答题】简述分布式文件系统
【单选题】What is said about the rainfall in America's West?
A.
There is much more rainfall in California than in Utah.
B.
The water it delivers becomes lighter when it moves inland.
C.
Its chemical composition is less stable than in other areas.
D.
It gathers more light isotopes as it moves eastward.
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