问题补充：
He go to work by bus, but now he riding a bicycle to work.
A. used to; used to
B. used to; is used to
C. is used to; used to
D. is used to; is used to
答案：
A. used to; used to
(答案→)B. used to; is used to
C. is used to; used to
D. is used to; is used to
解析：这里是考used to和is used to的用法。这里表示一种对比关系，以前是那样，现在不是那样了。
