请说明该句那句是主句,那句是从句 As is known to us,he is an artist

请说明该句那句是主句,那句是从句 As is known to us,he is an artist It is known to us how he became a writer.这句主语从句,那部分是主句,那部分是从 He is little known as an artist. what he wants to tell us is not clear.这句话是主语从句,具体分解一下那部分是主句, 连词成句:be,is,going,amy,to,artist,an He is going to be an artist（同义句）要快! He is going to visit an artist tomorrow.(visit an artist是画线部 when是引导时间状语重句的,如果主句是过去时从句是过去进行时,那为什么句子是When he was young ,he when是引导时间壮语重句的,如果主句是过去时从句是过去进行时,那为什么句子是When he was young ,he 英语达人进我老师说如果有介词引导的从句是主句,并且在句首的话,就是宾语从句 那Aftetr what seems an 英语句形转换,1.that he is a famous singer is known to us.（变成形式主语）2 he is not as friendly to us as his sister.(同义句转换) his sister