—Are you a volunteer now?
—No, but I . I worked for the City Sports Meeting last year.
A. used to
B. used to be
C. used to do
D. was used to
网友回答
A. used to
(答案→)B. used to be
C. used to do
D. was used to
解析：考查词组和省略式，used to do“过去常常’,be used to do “被用来做”，句意是：--你现在是志愿者吗？--不但我过去是，去年我为市运动会工作。可以排除D项，因为这是省略句，完整的是I used to be a volunteer。英语中如果不定式的部分是重复上文可以省略to后面的内容，但是如果to后面是be动词或助动词have，就不省略。选B。