famous的同义词well-known,为什么有横杠呢?还有known,

famous的同义词well-known,为什么有横杠呢?还有known,
know后面还有一个n呢

known是know的过去分词
1.出名的,众所周知的[(+for/as)]
He is one of the world's best-known opera singers.
他是世界上最有名的歌剧演员之一.
2.熟知的
She sang an old well-known song.
她唱了一首大家熟悉的老歌.
For reasons well-known to all, I had to cancel the trip.
鉴于众所周知的缘故,我不得不取消这次旅行.
well-known与well know的区别：
一是做定语,一是作表语;一个是形容词,一是短语.
有-的通常作为‘著名的’意思做为定语修饰名词.
而无-的两个是分开的,可以单独用KNOWN,如加WELL这个修饰语,同样也是有名的意思,但通常是做为系表结构的表语接在系动词之后.