聚集是一种( )措施。
A) DDL B) DML C) 优化 D) 面向对象
参考答案：C
She _____ have left school, for her bike is still here. [ ]
A. can't
B. wouldn't
C. shouldn't
D. needn't
黄精具有的功效是（）
A.补肺气、养肺阴
B.补脾气，养脾阴
C.滋阴平肝，清肝降火
D.补益肾精
E.补血
