質問: Why is に used in this sentence? > > 彼は彼女に見覚えがある。 > > > Also, why is 見覚え marked by が?
回答: 見覚え is a noun here, hence it's marked with が as the subject of ある. 見覚えがある is a set phrase meaning "to recognize" by sight. The particle に here marks that *in* which one finds *familiarity*. Thus, > > 彼は彼女に見覚えがある > > > means "He recognizes her".