现在分词完成式having been done和过去分词done的用法区别
having been done和done的意义有时非常接近,那就是它们都可以表示发生在谓语动词前的被动动作,甚至有时可以互换.例如：
Having been weakened by successive storms,the bridge was no longer safe.
= Weakened by successive storms,the bridge was no longer safe.
但下列情况只用done：
过去分词done只表示被动,不表示特定的一次,也没有一定的时间性,例如：
Seen from on the top of the hill,the park looks more beautiful.
2.过去分词done只表示状态,不表示动作,例如：
The road was covered with fallen leaves.
United,we stand; divided,we fall.
3.过去分词done只表示完成,不表示被动,这类动词一般由不及物动词产生,例如：
With all his friends and money gone,he felt helpless.
这样的动词还有,fallen,boiled,baked,developed等.
4.现在分词having been done一般不能作后置定语,用过去分词替换,但作非限制性的后置定语是可以的.例如：
The question having been discussed for thousands of years has now been solved.
(×)
The question discussed for thousands of years has now been solved.( √)
The question,having been discussed for thousands of years,has now been solved.( √)
