--- Where is your great-grandmother your mother’s side from?
--- She is from Beijing．
A. by
B. on
C. at
D. of
网友回答
A. by
(答案→)B. on
C. at
D. of
解析：Family of grandmother and grandfather on mother's side指“外祖父，外祖母”，句意：--你外祖母从什么地方来？--她来自北京。By“通过”，at“在…地方”，of“…的”，都不能用于这个词组。选B。