设有关系R(A,B,C,D),其函数依赖集F={A→B,A→C,B→D},则关系R至多满足
A.1NF
B.2NF
C.3NF
D.BCNF
参考答案:B
伤口污染轻,清创术可延长时限至()
A.12小时内
B.16小时内
C.20小时内
D.24小时内
E.以上均不对
What could have()her ()this state of despair?
A.brought;to
B.brought;on
C.brought;about
D.brought;forward