由 had 加動詞的過去分詞構(gòu)成。
　　例句：
　　She said she had never been to Paris. 她說她從未去過巴黎。
　　When the police arrived,the thieves had run away. 警察到達時，小偷們早就跑了。
　　By the time he was twelve,Edison had begun to make a living by himself. 到了十二歲那年，愛迪生開始自己謀生。