请专家回答base on & be based on

今天忽然看见练习上有这么个题目, Father Christmas ______ a real person in history. A. base on B. is based on
开始想着是选B的,但仔细一想,A难道有错吗......

focus on 与 base on base on /be based on 问~~~~请专家回答~~~~~~~ 急！专家请回答 请专家回答~~~ 妇科专家请回答。 请专家回答！谢谢！ 心里专家请回答 请专家来回答 请骨科专家回答？