Ⅰ. known as “作为…而出名”;“被称作…”，as后面的宾语与句子主语是同位的。如：
① George is known as a successful banker. 乔治作为成功的银行家而出名。
② The first tomb, known as Chang Ling, was built in the 15th century. 第一座陵墓叫长陵修建于是5世纪。
Ⅱ. known by “凭……来判断或认识”一般不太常用，多出现在某些谚语中。如：
① A man is known by the company he keeps. (谚)见其友，知其人。
Ⅲ. known for “因……而出名”，for后面多接表示特征、品质之类的词。如：
① Guilin is known for its beautiful sceneries. 桂林因风景优美而闻名。
② He is known for his frankness. 他以坦率而出名。
Ⅳ. known to “为……所知的”，to后面常接表示人的名词或代词。如：
① She is known to everyone in the college. 他在学院里人人皆知。
② The usage of that word is known to us all. 这个词的用法我们人人皆知。