Mary _____ go to school by bike, but now
题型：选择题
问题：
Mary _____ go to school by bike, but now she usually takes a school bus to school. [ ]
A. used to
B. had to
C. was afraid to
D. preferred to
Mary _____ go to school by bike, but now she usually takes a school bus to school. [ ]
A. used to
B. had to
C. was afraid to
D. preferred to