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延續動詞與瞬間動詞
1)用於完成時的區別
延續動詞表示經驗、經歷; 瞬間動詞表示行為的.結 果，不能與表示段的時間狀語連用。
He has completed the work. 他已完成了那項工作。 (表結果)
I've known him since then. 我從那時起就認識他了。(表經歷)
2)用於till/until從句的差異
延續動詞用於肯定句，表示"做……直到……" 瞬間動詞用於否定句，表示"到……，才……"
He didn't come back until ten o'clock.
他到10 點才回來。
He slept until ten o'clock.
他一直睡到10點。
典型例題
1. You don't need to describe her. I ___ her several times.
A. had met B. have met C. met D. meet
答案B. 首先本題後句強調對現在的影響，我知道她的模樣，你不用描述。再次，several times告知為反覆發生的動作，因此用現在完成時。
2.——I'm sorry to keep you waiting.
——Oh, not at all. I ___ here only a few minutes.
A. have been B. had been C. was D. will be
答案A. 等待的動作由過去開始，持續到現在，應用現在完成時
過去完成時
1) 概念：
表示過去的過去
其構成是had +過去分詞構成。
那時以前 那時 現在
2) 用法
a.在told, said, knew, heard, thought等動詞後的賓語從句。
She said (that) she had never been to Paris.
b. 狀語從句
在過去不同時間發生的兩個動作中，發生在先，用過去完成時;發生在後，用一般過去時。
When the police arrived, the thieves had run away.
c. 表示意向的動詞，如hope, wish, expect, think, intend, mean, suppose等，用過去完成時表示"原本…，未能…"
We had hoped that you would come, but you didn't.
3)過去完成時的時間狀語：
before, by, until , when, after, once, as soon as.
He said that he had learned some English before.
By the time he was twelve, Edison had began to make a living by himself.
Tom was disappointed that most of the guests had left.
