问题补充:
— Is your mother still a teacher?
— .
A. Yes, she was
B. She didn’t use to
C. No, but she used to
D. No, but she used to be
答案:
A. Yes, she was
B. She didn’t use to
C. No, but she used to
(答案→)D. No, but she used to be
解析:选D。used to be表示“曾经是……”,与现在有对比之意。to后的be要保留。