过去完成时的概念：
过去完成时既可表示过去某个时间或动作之前所发生的事情，也可表示过去某个时间或动作之 前所发生的动作一直持续到过去某个时间。过去完成时由“had+过去分词”构成。
如：She had leant 2000 English words by the end of last month.
过去完成时的应用：
（1）与过去完成时连用的时间状语可以多种多样，使用它的主要依据是看其是否发生在“过去的过去”。
如：He had learnt some English before I went here. 在来这儿之前我学过一些英语。
He had written three stories by last year.到去年他已经写了三篇故事。
We had cleaned the room when he got there. 当他到那儿时，我们已经把房子弄干净了。
He went there after he had finished his work. 他把事做完之后，就去哪儿了。
注意：当主句跟由before, after, as soon as所引导的时间从句的动作连接很紧密时，从句也可用一般过去时。
如：He went there after he read the letter. 他看了那封信后就去那儿了。
（2）过去完成时还经常用于主句为过去时的宾语从句中。
如：He said he had been a soldier. 他说他当过兵。
They said they had seen the film. 他们说这幕电影他们看过。
（3）在hardly/scarcely…when…,nosooner…than…两个结构中的主句通常要用过去完成时。
如：Hardly had I told her the news when she began to cry out. 她一听到这一消息就大哭了起来。
Scarcely had he finished his supper when he went out. 他已吃完晚饭就出去了。
No sooner had he fallen asleep than he lay down on the bed. 他一躺倒床上就睡着了。
（4）动词expect, hope, suppose, think, want等的过去完成时可用来表示未实现的计划、打算或希望。
如：I had hoped to see you. 我本希望来看你。
He had wanted to buy a house in Beijing. 他本想在北京买栋房子。
过去完成时与一般过去时：
（1）过去完成时表示以过去某时间为起点以前所发生的动作或存在的状态，即：过去完成时强调“过去的过去”，而一般过去时只表示以现在时间为起点以前所发生的事情或存在的状态。
如：He studied there two years ago. 他在那儿学习了两年。(离现在两年)
He said he had studied there two years ago. 他说他在那儿学习了两年。(离他说话时两年)
（2）表示过去某个时间以前所连续发生的两个或两个以上的动作时，一般用and, then, but按照动作的先后顺序连接，此时通常用一般过去时而不用过去完成时。
如：He said he went the shop and bought some food. 他说他去商店买了一些食品。
（3）两个动作相继发生，可用一般过去时；如第一个动作需要若干时间完成，用过去完成时。
如：When I heard the news, I was very excited.
（4）叙述历史事实，可不用过去完成时，而只用一般过去时。
如：Our teacher told us that Columbus discovered America in1492.
部分倒装的概念：
倒装英语句子的主语通常位于谓语动词之前，这种语序被称为正常语序。但有时出于修辞或某种特殊的语法结构的需要，需要将谓语动词放在主语之前，这种语序则叫倒装语序。主语和助动词倒置叫部分倒装。
部分倒装：
1、含有否定意义的副词位于句首时的倒装：
在正式文体中，never, seldom, rarely, little, hardly, scarcely, no sooner, no longer, nowhere等含有否定意义的副词若位于句首，则其后要用部分倒装：
如：I shall never forgive him./ Never shall I forgive him. 我永远不会宽恕他。
He seldom goes out for dinner./Seldom does he go out for dinner. 他很少出去吃饭。
She hardly has time to listen to music./Hardly does she have time to listen to music. 他几乎没时间听音乐。
He little realize show important this meetingis./Little does he realize how important this meeting is. 他不甚明白这个会议的重要性。
We had no sooner reached the airport than the plane took off./No sooner had we reached the airport than the plane took off. 我们刚到机场,飞机就起飞了。
注：(1)对于not…until句型，当not until…位于句首时，其后的主句要用倒装语序：
如：He didn't leave the room until the rain stopped./Not until the rain stopped did he leave the room. 雨停了之后他才离开这房间。
(2)某些起副词作用的介词短语，由于含有否定词，若位于句首，其后要用部分倒装：
如：On no accounts must this switch be touched. 这个开关是绝不能触摸的。
In[Under] no circumstances will I lend money to him. 无论如何我也不会再借钱给他了。但是，in no time(立即，马上)位于句首时，其后无需用倒装语序：
如：In no time he worked out the problem. 他马上就算出了那道题。
2、“only+状语”位于句首时的倒装：
当一个状语受副词only的修饰且置于句首时，其后用部分倒装语序：
如：Only then did he realize that he was wrong. 到那时他才意识到他错了。
Only in this way are you able to do it well. 你只有用这种方法才能把它做好。
Only when he returned home did he realize what had happened. 当他回到家里时,才知道出了什么事。
3、“so+形容词或副词”位于句首时的倒装：
副词so后接形容词或副词位于句首时，其后用部分倒装：
如：So cold was the weather that we had to stay at home. 天气太冷，我们只好呆在家里。
So fast does light travel that we can hardly imagine its speed. 光速很快，我们几乎没法像它的速度。
So sudden was the attack that we had no time to escape. 袭击来得非常突然，我们来不及逃跑。
4、“So+助动词+主语”倒装：
当要表示前面提出的某一肯定的情况也同样适合于后者，通常就要用“So+助动词+主语”这种倒装结构：
如：You are young and so am I. 你年轻，我也年轻。
She likes music and so do I. 她喜欢音乐，我也喜欢。
If he can do it, so can I. 要是他能做此事，我也能。
注：(1)若前面提出某一否定的情况，要表示后者也属于同样的否定情况，则应将其中的so改为neither或nor：
如：You aren't young and neither am I. 你不年轻，我也不年轻。
She hasn't read it and nor have I. 她没有读它，我也没有读。
(2)注意该结构与表示强调或同意的“so+主语+特殊动词”结构的区别：
如："It was cold yesterday." "So it was."“昨天很冷。”“的确很冷。”
"Father, you promised." "Well, so I did."“爸爸，你答应过的。”“嗯，是答应过。”
5、由not only…but also引出的倒装：
当not only…but also位于句首引出句子时，not only后的句子通常用部分倒装形式：
如：Not only is he a teacher, but he is also a poet. 他不仅是一位教师，而且是一位诗人。
Not only did he speak more correctly, but he spoke more easily. 不仅他讲得更正确，也讲得更不费劲了。
6、虚拟条件句省略if后构成的倒装：
当if引导的虚拟条件从句中含有had, were, should等时，如将if省略，则要将had, were, should等移到主语前，构成倒装句：
如：Had you come yesterday, you would have seen him. 若你昨天来，你就会见到他了。
Should you require anything give me a ring. 如果需要什么，可以给我打电话。
Were it not for your help, I would still be homeless. 要不是你帮助，我会仍然无家可归。
注：省略if后提前的had不一定是助动词：
如：Had I money, I would buy it. 假若我有钱，我就会买它。