莫里亚蒂教授是福尔摩斯最危险的对手。

Professor ___Moriarty is Sherlock Holmes' most dangerous adversary.

在侦探小说中，主角的对手是一个像莫里亚蒂那样狡猾的犯罪天才。

In the detective novel, the protagonist faces an opponent as cunning as ___Moriarty.