Samuel Clemens, Mark Twain, because a famous American writer.
A. was known as
B. known as
C. was known for
D. known for
网友回答
A. was known as
(答案→)B. known as
C. was known for
D. known for
解析：考查非谓语动词。Be known as作为某种人物出名；known for以某事出名。句意：克莱门斯，以马克吐温的身份著名，成为一个著名的小说家。过去分词表示被动的发生过的动作，前面不用助动词，故选B。