had+done 与have+done有什么区别?举例

现在完成时
（The simple present perfect tense）是由have/has的现在式 + 过去分词构成的。规则动词的过去分词形式一般过去时相同，不规则动词则可能不同。
在英语中，现在完成时有两种用法：
1）表示开始于过去并持续到现在（也许还会持续下去）的动作。
2）表示在过去不确定的时间里发生过或未发生过的动作，该动作与想在有某种联系。
A.开始于过去并持续到现在的动作
当我们讲述开始于过去，并持续至现在或讲话时刚刚结束的动作时，经常使用现在完成时。例如，
I've planted fourteen rose-bushes so far this morning.
I've just tidied up the kitchen.
It's the most interesting book I've ever read.
I've often wondered where she gets her money.
B.已完成的动作或事件
当过去事件刚刚结束并对现在情况有较大影响时，常用过去完成时来讲述。例如，
The president has been assassinated.
Utopia has declared war on Fantasia.
I can't go on holiday because I've broken my leg.
Jason Villiers has been arrested.
C.与since和 for连用的现在完成时
since与for常与现在完成时连用，表示直到现在的时段。since + （时点）可用作：
连词：Tom hasn't been home since he was a boy.
副词：I saw Fiona in May and I haven't seen her since.
介词：I've lived here since 1980.
“for + 时段”常与现在完成时连用，表示某事已经进行了多久。例如，
He's lived in London for ten years.
We've known each other for a long time.
She's worked here for 35 years.

一般过去完成时
过去完成时（The simple past perfect tense）由had + 过去分词构成。其主要用法是表示两个事件哪一个发生在前。如果仅仅是讲述发生在过去的事情，应该用一般过去时。例如，
The mother died.母亲去世了。
Her son came back.儿子回来了。
用不同的方式把这两个句子结合起来，可以表明它们不同的过去时间关系。
The mother died when her son came back.
儿子回来时，母亲去世了。（即母亲的去世是在儿子刚刚回来的时候）
The mother had died when her son came back.
儿子回来时，母亲已经去世了。（即母亲的去世是在儿子回来以前）
A.用于said,told等讲述性词语之后。
过去完成时经常用于asked, explained, said,told ，thought, wondered等讲述性词语后，表示在谈话或产生某种想法之前发生的事情。例如，
I asked if he had invited Mr Cary to the party.
I explained that I had left the documents in my office.
She said that she had met him once before.
I told them that I had done enough work for one day.
I thought I had sent the check a week before.
She wondered who had left the door open.
B.与when, after, as soon as, by the time等连词连用。
某些典型的连词常用在过去完成时之前，表示“较早的过去”，如after,as soon as, when,这些词往往内含因果关系。例如，
She didn't feel the same after her husband had died.
We cleared up as soon as our guest had left.
I did some gardening when I had written all my letters.
When I had washed the dog, it ran off into the bushes in disgust.
By the time I got downstairs, the telephone had stopped ringing.
By the time I recovered from the shock, he had disappeared.
When I had put the dog out, I locked the door and went to bed.
(Not: When I put the dog out, I locked ...)
C.常与过去完成时连用的副词
常与现在完成时连用的副词，如already,ever, for +(表时段的词),just,,never, never...before,before,since+(表时点的词)也常与过去完成时连用。例如，
The doctor arrived quickly, but the patient had already died.
He offered me a drink before I had taken off my coat.
She asked me if I had ever been in trouble with the police.
I had not seen him for a month.
He had just gone out when you came here.
Juliet was excited because she had never been to a dance before.
She had worked here since 1967.
D.表示未能实现的希望或愿望
我们可用expect,hope,mean,suppose, think , want,wish等动词的过去完成时来表示我们想做而未做的事情。
例如，
I had expected that we could share the hard time together.
I had hoped that we would be able to leave tome , but it's beginning to look difficult.
I had supposed that it was not the truth.
I had intended to make a cake, but I ran out of time.
I had wanted to stand by his side forever.
Note：
我们不一定非得用过去完成时表示过去先发生的事件，因为有时句意非常清楚。例如：
After I finished my work, I went home.
在关系从句中，动作的顺序往往十分清楚，例如：
I wore the necklace (which) my grandmother (had) left me.
我们通常用一般过去时表示依次发生的事件。例如：
I got out of the taxi, paid the fare, tipped the driver and dashed into the station.
Mary said some rather horrible things to me, I felt pretty upset, but tried not to think about it too much.

过去完成时：（过去的过去做过）
用had+过去分词
例：He told us that he had finished his homework.
分析：他告诉我们的时候已经是过去时
而做完作业是在他说之前发生的
也就是过去的过去，所以用had done
现在完成时：（现在之前做过）
用have+过去分词
例：He have finished his homework now.
分析：目前对于他而言已经完成了
也就是现在完成了，所以用had done

现在完成时（The simple present perfect tense）是由have/has的现在式 + 过去分词构成的.规则动词的过去分词形式一般过去时相同,不规则动词则可能不同.在英语中,现在完成时有两种用法：1）表示开始于过去并持续到现...

had是过去完成时
have是现在完成时
如果你想说，到现在为止，已经．．了．用have
如果是在过去的某一时间，就已经．．了，用had