问题补充：
---- you a bus to school?
---- Yes. But now I usually go to school on foot.
A. Do, like to take
B. Do, take
C. Did, used to take
D. Are, used to taking
答案：
A. Do, like to take
B. Do, take
(答案→)C. Did, used to take
D. Are, used to taking
解析：根据“But now I usually go to school on foot.”句意，应指过去。故选C。used to do指“过去常常做某事”
