Miss Smith is a friend of .A. Mary’s mother’sB. the mother of MaryC. mother of Mary’sD. Ma

问题补充：

Miss Smith is a friend of .

A. Mary’s mother’s

B. the mother of Mary

C. mother of Mary’s

D. Mary’s of mother

答案：

(答案→)A. Mary’s mother’s

B. the mother of Mary

C. mother of Mary’s

D. Mary’s of mother

解析：双重所有格用法。