-____ subject do you like, English or PE?
-I like PE. [ ]
A. What
B. How
C. Which
答案:C
设有两个关系R(A,B)和S(B,C),与下列SELECT语句
SELECT A,B
FROM R
WHERE B NOT IN(SELECT B
FROM S
WHERE C=‘C56’);
等价的关系代数表达式是()。
A.A
B.B
C.C
D.D
垂体催乳素腺瘤引起的闭经,体内垂体卵泡刺激素水平通常是()
A.增高
B.降低
C.波动很大
D.持续下降
E.测不出