现在完成时讲解
一、基本结构：
1、肯定句：主语+have/has+过去分词(done)+------.
2、否定句：主语+have/has+not+过去分词+------.
3、一般疑问句：Have/Has+主语+过去分词+------.
回答: Yes, 主语 + have/has.(肯定)
No, 主语 + haven't/hasn't.(否定)
二、用法
（1）现在完成时表示过去发生或已经完成的动作对现在造成的影响或结果
I have spent all of my money. (含义是:现在我没有钱花了.)
Lily has (just/already) come. (含义：Lily现在在这儿)
My father has gone to work.(含义是:我爸爸现在不在这儿)
（2）现在完成时可以用来表示发生在过去某一时刻的, 持续到现在的动作或状态，常与for （+时间段）,since（+时间点或过去时的句子）连用.
①for+时段
②since+过去时间（译为：自从……以来）
③since+从句（过去时）
④It is+时段+since+从句（过去时）
Mary has been ill for three days.
I have lived here since 1998.
三、has gone (to), has been (to), has been (in)的区别
1、Have/Has gone(to) :去了(现在不在说话现场)
Where is your fatherHe has gone to Shanghai.
2、Have/Has been (to) :去过（已不在去过的地方）
My father has been to Shanghai.
3、Have/has been in：呆了多久（还在所呆的地方）
My father has been in Shanghai for two months. /since two months ago.
四、现在完成时的标志
1、现在完成时的含义之一是过去完成的动作对现在仍有影响,用以下四大标志词可以表达这种含义:
（1）以already, just和yet为标志
He has already got her help.他已得到她的帮助。
He has just seen the film.他刚刚看过这场电影。
He hasn't come back yet.他还没有回来。
（2）以ever和never为标志
This is the best film I have ever seen.这是我曾经看过的最好的一部电影。
He has never been to Beijing.他从没有到过北京。
（3）以动作发生的次数为标志
He says he has been to the USA three times. 他说他已经去过美国三次了。
（4）以so far（到目前为止）为标志+before
He has got to Beijing so far.到目前为止他已到了北京。
She has passed the exam so far.到目前为止她已经通过了考试。
2.过去已经开始的动作一直延续到现在, 甚至有可能继续延续下去,我们可以从动作“延续”的特性和“时间”点段的区分入手,进一步学习现在完成时。
①for+时段
②since+过去一个时间点（过去从句）为标志
注意：
1)现在完成时不能单独与过去的时间状语连用,如yesterday, last week, three years ago等;
五、过去分词
（一）规则动词：规则动词的过去分词的构成规则与规则动词的过去式的构成规则相同。
(1) 一般动词，在词尾直接加“ ed ”。
work---worked---worked ,visit---visited---visited
(2) 以“ e ”结尾的动词，只在词尾加“ d ”。
live---lived---lived ,
(3) 以“辅音字母+ y ”结尾的动词，将"y" 变为"i" ，再加“ ed ”。
study---studied---studied ,cry---cried---cried
(4) 重读闭音节结尾，末尾只有一个辅音字母，先双写该辅音字母，再加“ ed ”。
stop---stopped---stopped , drop---dropped--dropped
（二）不规则动词：
1、AAA型
原型过去式过去分词
burst burst burst cast cast cast cost cost cost cut cut cut
hit hit hit hurt hurt hurt let let let put put put
set set set shut shut shut spread spread spread
read read read read原形发音为/ri:d/,过去式和过去分词发音为/red/
2、AAB型
beat beat beaten
3、ABA型
become became become run ran run come came come
特殊情况
4、ABB型
bring brought brought buy bought bought build built built burn burnt burnt catch caught caught
dig dug dug
feel felt felt fight fought fought find found found
hear heard heard hold held held
keep kept kept
lay laid laid lead led led lose lost lost
make made made meet met met
sell sold sold shoot shot shot sit sat sat stand stood stood
sweep swept swept
teach taught taught tell told told think thought thought
win won won
5、ABC型
begin began begun blow blew blown break broke broken
choose chose chosen
draw drew drawn drive drove driven drink drank drunk
fly flew flown forgive forgave forgiven forget forgot forgotten freeze froze frozen
