英语语法求分析She was the first to learn about it.这句中,She was the f

英语语法求分析
She was the first to learn about it.
这句中,She was the first是主系表结构我知道,后面的动词不定式在这里是做定语还是状语.我在网上搜了,有的说定语有的说状语,从我的了解中,定语用来修饰名词或者代词,状语是谓语的附加成分,因为理解水平有限,我把状语暂且看作是对谓语的修饰.在这句话中,我觉得动词不定式to learn about it是对the first这个名词的修饰,所以我看做是定语.
不知道我的理解是否有误,希望得到各位老师的指点.