--Is your father a teacher?
---well, he .
A. used to
B. was used to
C. used to be
D. is used to be
网友回答
A. used to
B. was used to
(答案→)C. used to be
D. is used to be
解析：C 考查used to的用法。“过去常常做……”used to do sth.,“习惯于......”be used to doing sth.“曾经是老师”, used to be中be的不能省略。