成人骶管容积为（）
A.20～25ml
B.25～30ml
C.30～35ml
D.35～40ml
E.40～45ml
参考答案：B
This is apple. It’s big apple. apple is for you.
A．a/ a/ The
B．an/ the/ An
C．the/ a/ The
D．an/ a/ The
