问题补充：
--- Didn’t your brother go to school by bike?
--- Yes, he did. But he walking to school now.
A. used to; used to
B. use to; used to
C. used to; is used to
D. use to; is used to
答案：
A. used to; used to
B. use to; used to
C. used to; is used to
(答案→)D. use to; is used to
解析：句意：----你弟弟过去不是骑车去上学的吗？----不，他是骑车去的。但他现在习惯步行去上学。本题考查used to 和be used to 的用法区别.used to 表示过去常常做某事，而be used to 表示习惯于做某事，后接动词ing形式。在一般疑问句中，used to 用原型use to 。故选D。
