非谓语having

非谓语中的having done是现在分词的完成式，它表示主动的动作，并且动作发生在谓语动词之前，常常作状语来修饰动词。

（1）having done 是非谓语动词中现在分词的完成式。与现在分词一般式doing 相比，doing表示的动作或状态往往与句子谓语动词表示的动作或状态同时发生，而having done 强调在谓语动词之前发生。having done 通常在句中作状语，表示句子主语发生的动作或存在的状态，与主语是主动关系。

（2） having done 作状语，可以变成相应的完成时的状语从句。

（3） having done 的被动式为having been done， 与句子主语之间是被动关系。

例句

Not having had anything for the whole day， he wolfed down three bowls of rice。

Having seen him before， I know what he is like。

Having graduated from high school， he became a journalist。

The USA is a developed country。

The problem discussed yesterday was how to use the sixteen tenses in English。