不同的词典对as词类的标注是不同的。

《韦氏词典》

as

 pronoun

Definition of as (Entry 3 of 9)

1: THAT, WHO, WHICH —used after same or such

in the same building as my brother…

tears such as angels weep …

— John Milton

and chiefly dialect after a substantive not modified by same or such…

that kind of fruit as maids call medlars …

— William Shakespeare

2: a fact that

is a foreigner, as is evident from his accent