[have 的过去式和过去分词，主要动词，助动词和情态动词(had to)]
主要动词:Have you had lunch? 助动词 :It had rained all night.情态动词:I had to see the doctor.
had 用作主要动词的结构和have是一样的:
They had no friends. We had a nice chat.
语法结构
1 had | + 过去分词
The film had already started when we got there.
At the airport I realized I had left my passport at home.
Until last week,it hadn't rained in the region for several years.
从过的某一个点往回看，表示在那个时间之前发生的事情.(这也叫做过去完成时)
Stephen told me he had found a new agent.
The doctor asked him if he had ever had hepatitis.
转述人们所说的或所问的有关过去的事。
2 had | + been | + -ing
It had been raining heavily all morning,and the roads were still slippery.
Before he moved to Toronto he had been living in Vancouver.
从过去的某一个点往回看,表示到那个时间点之前一直在进行的事情。(这叫做过去完成进行时)
3 had | + been | + 过去分词
They told me that the house had just been sold.
Before I bought it ,the car had been owned by a retired professor.
从过去的某一个点往回看,表示在那个时间之前受某一行为影响的事情。
(这叫做过去完成时被动语态)
4 if | + had分句(过去完成时), | + 分句 (would have/could have等)
if we had booked,we would have got a table.
5 had | + 名词短语 | + 过去分词, | + 分句(would have/could have等)
Had we been informed of the situation,we would have acted accordingly.
语法结构4的一种更正式的表达法。
6 had | + 带to的不定式
did | + not | + have | + 带to的不定式
I'm sorry I'm late but I had to take the kids home.
It snowed so much they had to close the airport.
Because it was a holiday,Emma didn't have to work on Monday.
表示必要的、 有义务要做的事()或没必要、没义务要做的事.
7 had | + better | ( + not ) | + 动词原形
Look at you! You're soaking wet.You had better come in and dry off.
We'd better not tell Rob,or he'll want to come too.
表示你认为某事应该(或不应该)发生,提建议。
搭配
在过去完成时里最常用的一些动词是:be,make,go,come,take,see,have,say和leave.
It had been ages since I had last seen Felicity.
We'd made good progress by the time the snow started.
在过去完成时里最常见的副词有: never,already,ever,always,just,once.
Before I went to Finland,I'd never had a sauna.
Although we'd already eaten,we accepted their offer of a snack.
It was the first time I had ever seen a yak.
This was not my first visit.I had been there once before.
固定短语
'have had it '= be in a bad condition,be in serious trouble情况不好,深陷麻烦
The TV has had it,it's time we got a new one.
I lost Jim's digital camera.~Now,you've had it.