—Are you a volunteer now?—No but I . I worked for the City Sports Meeting last year.A. us

问题补充：

—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

答案：

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。