2016年職稱英語衛(wèi)生類考試時態(tài)之過去完成時：

過去完成時：過去完成時表示過去某一時間或某一動作發(fā)生之前已經(jīng)完成的動作。簡言之, 過去完成時所表示的時間是“過去的過去”。

①過去完成時由“助動詞had+動詞的過去分詞”構(gòu)成。

②過去完成時時間狀語有：by (yesterday), by then, by the end of (last…)或者由when,before等引出狀語從句。有時句子中會有already, just, once, ever, never等詞語,也會有for… 或since…構(gòu)成的時間狀語。如：They had already finished cleaning the classroom when their teacher came.(當(dāng)老師來的時候他們已經(jīng)打掃完了教室)/ The woman had left before he realized she was a cheat.(在他發(fā)覺那個婦女是個騙子時她已經(jīng)走掉了)

③過去完成時常用于賓語從句中、after引導(dǎo)的從句中,或者從句是before引導(dǎo)的主句中。如：After I had put on my shoes and hat,I walked into the darkness.(我穿上鞋子戴上帽子走進了黑暗之中)/ He said that he had never seen a kangaroo before.(他說他以前從來沒有見過袋鼠)