髁突关节表面带胶原纤维为（）
A.Ⅰ型胶原
B.Ⅱ型胶原
C.Ⅲ型胶原
D.Ⅳ型胶原
E.Ⅴ型胶原
参考答案：A
Mary is a humorous and warm-hearted woman and that is she is a most popular person in her community．
A．why
B．because
C．how
D．whether
