having spent some time in the city...求高手解释这是什么时态吖?have用现在分词,spent是过去分词.

having done
叫动名词的完成式,相当于过去完成时,是非谓语的一种,你的例句应该后面还有一个过去式的句子,表示,having spent some time in the city,在你后面的动作之前就发生了过去的过去以前，就用动名词的完成形式是吧？还要看逻辑主语和非谓语动词是不是主谓关系举个例子可以不？having spent the whole morning, i went home with an empty bag没有连词，谓语动词是went,spent要处理成非谓语，i 和spend是主谓关系，本应该用spending ,但是，又是过去的过去，就用 having spent=i had spent the whole morning before i went home...=having spent he whole morning ,i went home with an empty bag