对于大学英语四六级考试来说，语法非常重要。坚实的语法是英语水平进阶的充分必要条件。但现实情况是，不少人对语法学习并没有一个清晰的概念，甚至忽视语法学习。在此小编希望考生们重视起最语法的复习。今天文都四六级网给大家盘点2020年上半年大学英语六级语法：过去完成时，希望对您有所帮助。
大学英语六级语法：过去完成时
1) 概念：表示过去的过去
----|-------|-----|---->其构成是had +过去分词构成。
那时以前 那时 现在
2) 用法
a. 在told, said, knew, heard, thought等动词后的宾语从句。
She said (that) she had never been to Paris.
b. 状语从句
在过去不同时间发生的两个动作中，发生在先，用过去完成时;发生在后，用一般过去时。
When the police arrived, the thieves had run away.
c. 表示意向的动词，如hope, wish, expect, think, intend, mean, suppose等，用过去完成时表示"原本…，未能…"
We had hoped that you would come, but you didn't.
3) 过去完成时的时间状语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 when he arrived at the party.
典型例题
The students ___ busily when Miss Brown went to get a book she ___ in the office.
A. had written, left B，were writing, has left C. had written, had left D. were writing, had left
答案D. "把书忘在办公室"发生在"去取书"这一过去的动作之前，因此"忘了书"这一动作发生在过去的过去，用过去完成时。句中when表示的是时间的一点，表示在"同学们正忙于……"这一背景下，when所引导的动作发生。因此
前一句应用过去进行时。
注意： had no … when 还没等…… 就……
had no sooner… than 刚…… 就……
He had no sooner bought the car than he sold it.
语法的学习过程会觉得条目繁多，很难记，而且枯燥无味，这种情况下，学习应该寻找的是语法的学习方法。掌握方法，在学习过程中才能克服困难。更多四级语法、六级语法请及时关注文都四六级网站。
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