be worth doing和be worthy to be done

worth是介系词，后面只能跟动名词的主动形式，但表示被动的意义，如：
The book is worth reading.
If something is worth doing, it's worth doing well.
worthy是形容词，这个词的后面要跟介系词of，of之后才要跟动名词的被动式，或者直接跟动名词的被动式。如：
The book is worthy of being read.
If something is worthy to be done, it's worth to be done well.
另外，还有一个字叫做worthwhile，也是形容词，它可以作表语，后面可以用动词不定式和动名词，作其真正的主语：
It's worthwhile to read the book.
If it's worthwhile doing something, it's worthwhile doing it well.