濫竽

worth

是一个只能作表语的形容词，意思为“值……的”、“相当于……的价值的”、“有……价值的”、“值得……的”。后接名词、接动名词的主动形式。

be worth sth/ doing sth

This second-hand car is worth $2000 at the most.

The exhibition is worth a visit/visiting.

It's not worth getting angry with him.

The question is not worth discussing again and again.

worthy

可作表语，也可作定语。作定语时意思为“有价值的”、“值得尊敬的”、“应受到赏识的”；用作表语时意思为“值得……的”、“应得到……的”，常跟被动语态动词不定式或of加名词，或被动态动名词

be worthy of sth/ doing sth/ to be done

This book is worthy of being read.  =  This book is worthy to be read.

This is a worthy article.

作后置定语时，必须用“worthy of +名词”结构。例如：

There is nothing worthy of mention. 没有值得一提的事情。
 
注：“worthy of+动名词”与“worth+动名词”在形式上完全不同：worthy of后面接被动式的动名词；而worth后面接主动式的动名词，虽然在形式上是主动的，但其意义仍然是被动的。试比较：

The second-hand house is worthy of being bought. = The second-hand house is worth buying.

worthwhile

既可作表语，又可作定语。
表示某事因重要、有趣或受益大而值得花时间、金钱或努力去做，一般做“值得的”、“值得做的”、“有意义的”解。
用作表语时，可接动名词或动词不定式。

It is worthwhile doing sth/ to do sth.

表语
The Summer Palace is worthwhile going / to go to have a visit.

定语
Thank you for your worthwhile suggestion.