肱骨外上髁炎的病因主要是()。
A.急性化脓性感染
B.结核
C.类风湿
D.风湿
E.慢性损伤
参考答案:E
- There is something wrong with your bike, ___?
-Yes. I'll have it _ tomorrow.
A.isn’t it; mend
B.isn’t there: mended
C.isn't it; mended
D.isn't there; mend
有关系模式P(A,B,C,D,E,F,G,H,I,J),根据语义有如下函数依赖集:F={HIJ→E,IJ→G,J→F,C→B,C→A,G→D}。现将关系模式P分解为3个关系模式P1(C,E,F,H,I,J),P2(D,G,I,J),P3(A,B,C),则其中P2的规范化程度达到( )。
A.1NF
B.2NF
C.3NF
D.BCNF