当采用钻芯法检测时，受检桩的混凝土龄期应达到（）d，或受检桩同条件养护试件强度应达到设计强度要求。
A.7
B.14
C.21
D.28
参考答案：D
The package_______ a book and five CDs and the course________ many topics.
A. includes, covers B. including, is covered in
B. including, covers D. is included, is covered
民主就意味着平等。( )
