Task: Question Answering
Input (English): Context: She actually did quite a number on her tooth - even more than what you can see from the front . The back of the tooth is much more damaged . She 'll have to live with it ( and the teasing from her sister ) until next week when he 'll put a temporary on it , and then a couple weeks later , a porceline crown . He promises to have it all fixed by the beginning of the school year , because is n't this just how every 14 year old girl wants to start Gr . 
Question: What may be the reason for their injury ?
Output (English): They had fell and broke their tooth on the ground .