由 had 加動(dòng)詞的過去分詞構(gòu)成。
　　例句：
　　She said she had never been to Paris. 她說(shuō)她從未去過巴黎。
　　When the police arrived,the thieves had run away. 警察到達(dá)時(shí)，小偷們?cè)缇团芰恕?/div>
　　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。