关于非谓语动词做状语

题目

关于非谓语动词做状语
1.Having been delayed by heavy traffic,she found it impossible to arrive on time.
2.Anna was reading a piece of science fiction,completely lost to the outside world.
这两句同样是非谓语动词做状语,但是为什么一句用having been done而一句用done?

答案

第一句呢,用having been done,因为事情发生在过去的过去,遇到交通堵塞是发生在她知道要迟到之前的事情,所以叫过去的过去.
第二句是描述一个状态,两者同时发生,所以只要用过去时不需要用分词结构.