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【单选题】
如果用文件概念来命题的话,投影相当于从整个文件中各记录中抽出所要的( )。A.
项目
B.
集合
C.
属性
D.
卷
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【简答题】Judy arrived in Boston and wrote to her parents at once. Judy wrote to her parents ______ she arrived in Boston.
【简答题】A．Because her parents like traveling. B．Because her parents like history. C．Because traveling in such places costs less. D．Because her parents want to reinforce the stuff they learned in school about ...
【简答题】When she comes back, her parents would be very happy. ______, her parents are very happy.
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