问题补充:
——What’s your mother?
——She a teacher, but now she is a doctor.
A. used to be
B. was used to
C. use to be
D. is used to be
答案:
(答案→)A. used to be
B. was used to
C. use to be
D. is used to be
解析:根据后文答语内容, but now she is a doctor.可知答案为A,表示过去常常是···。