这是什么英语句式

After he had finishied his homework, he went out
------------- Can Change to
having finished his homework, he went out.

"having" is called a Present Participle

是现在分词作时间状语
例如：Walking along the road, I met an old friend .

过去完成时

having finished是非谓语中的分词形式，作状语，相当于一句时间状语从句——After he had finishied his homework ，因为后面有went作为动词，一个句子只能有一个谓语动词，所以只能用非谓语了。

什么倒装,肯定不是!我到认为那是现在分词作主语

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