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【单选题】
在数据库三级模式间引入两个映射的主要作用是（ ）[1分]A.
实现数据的并发控制
B.
提高数据的完整性
C.
实现数据独立性
D.
提高数据的可移植性
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【单选题】________advertisements, TV programs are often made boring. [ ]
A.
Regularly interrupted by
B.
Regularly interrupting
C.
To regularly interrupt
D.
To be regularly interrupted by
【简答题】已知 是椭圆 的两个焦点,P为椭圆 上的一点，且 .若 的面积为9，则 .
【简答题】A．Flies need less sleep than humans. B．Humans need a similar amount of sleep with flies. C．The amount of human sleep is determined by certain gene. D．Flies can determine how much sleep they need.
【简答题】A.aims B.agrees C.shoots D.flies
【简答题】若P为椭圆 上的一点, 为椭圆的两个焦点,则 的周长为 .
【单选题】Flies evolve to be smarter only in the labs fundamentally because______.
A.
flies can adapt to the environment without learning
B.
the cost of learning in the wild is too huge to bear
C.
they may get some diseases as a byproduct in nature
D.
the lab conditions allow them to learn better
【简答题】__________ time flies!
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