The external level defines the different __________ of the database.
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There will be many levels of abstraction between the computer and the ultimate user.
A. 对
B. 错
One user program usually requires all the data in the database.
A. 对
B. 错
Different views must contain altogether different data.
A. 对
B. 错
1、“酒”是指含有酒精、可饮用的液体，一般酒精含量为（），它会令人兴奋、麻醉，具有一定的刺激性。
A. 0、5%-75、5%
B. 0、5%-65、5%
C. 5%-75、5%
D. 5%-65、5%
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