问题补充：
The little girl,but her family was too poor at that time.
A. could go to school
B. could have gone to school
C. must have gone to school
D. can have gone to school
答案：
A. could go to school
(答案→)B. could have gone to school
C. must have gone to school
D. can have gone to school
解析：对过去事情表示猜测，应用情态动词的完成式。could have done表示“本有可能，但却没有”。
