4-1 现在完成式(Present Perfect Tense)
完成式的形式是 verb to have + past participle，每一个动词，都有过去式和过去分词，以下就是一些例子：
原式 过去式 过去分词(past participle)
go went gone
come came come
see saw seen
do did done
watch watched watched
get got gotten(或got)
have had had
use used used
buy bought bought
listen listened listened
draw drew drawn
paint painted painted
leave left left
arrive arrived arrived
dance danced danced
kill killed killed
write wrote written
run ran run
swim swam swum
snow snowed snowed
eat ate eaten
love loved loved
fly flew flown
spread spread spread
hit hit hit
drink drank drunk
take took taken
grow grew grow n
sell sold sold
ride rode ridden
steal stole stolen
break broke broken
walk walked walked
read read read
sing sang sung
work worked worked
以下的句子都是用了现在完成式：
I have read this book.
I have seen the movie.
I have lived here since 1973.
I have studied English for a long time.
He has washed his hands.
He has left.
He has already completed the report.
The storm has arrived.
I have taken the job.
I have written the letters.
I have not seen him since 1975.
I have never seen this man before.
什么情况之下要用现在完成式呢?
1.首先假设我们有一件事，发生在过去，而一直延续到现在，就要用现在完成式，这种句子后面常有since或for。以下是这种情形的例子：
(1)自从1963年，我一直在念英文。
I have studied English since 1963.
(2)自从1975年以后，我就住在这里。
I have lived here since 1975.
(3)自从我是一个小孩子，我就喜欢摇滚乐。
I have loved rock and roll music since I was a child.
(4)自从去年，我就从来没有见过他。
Since last year, I have never seen him.
(5)自从1950年以后，他就一直在此工作。
He has worked here since 1950.
(6)我认识他已经很久了。
I have known him for a long time.
(7)他练习网球已经四年了。
He has already practiced tennis for (the past) four years.
(8)我穿这件夹克很久了。
I have worn this jacket for a very long time.
(9)我开这辆汽车很久了。
I have driven this car for a long time.
(10)好久没有下雨了。
It has not rained for a long time.
2.使用现在完成式的另一情况是强调已经完成的事，比方说，你说〝我已经写了那封信〞，就可以用现在完成式，或者，你说〝他已经完成了工作〞。以下是这类的例子：
(1)我已经写了这封信。
I have already written the letter.
(2)他已经完成了工作。
He has already completed the work.
(3)我已经测试了这个程序。
I have already tested the program.
(4)我已经收到了你的信。
I have already received your letter.
(5)他已搬到了一个较大的房子。
He has already moved to a bigger house.
(6)虽然他很年轻，但他已写了三本小说。
Although he is young, he has already written three novels.
(7)我打了二次电话给他，他都没有回答。
I called him twice, he has never answered.
3.现在完成式用来表示一种经验，举例来说，〝我曾经到过美国〞、〝我曾见过李总统〞、〝我有生以来没有跳过舞〞，这些都应该用现在完成式，例如：
(1)我曾经到过美国。
I have been to America.
(2)我曾见过李总统。
I have seen President Lee.
(3)我有生以来没有跳过舞。
I have never danced in my life.
(4)我看过〝双城记〞。
I have read The Tale of Two Cities.
(5)他曾吃过这种冰淇淋。
He has tasted this kind of ice cream.
(6)我未曾见过雪。
I have never seen snow.
(7)你曾见过雪吗?
Have you ever seen snow?
(8)你登过玉山吗?
Have you ever climbed Jade Mountain?
4.现在完成式可以用来表示一件过去常发生的事：
(1)今年我国已有二次台风。
We have already had two typhoons so far this year.
(2)他今年已发表了三篇论文。
He has already published three papers this year.
(3)过去一年，我看了三次〝铁达尼号〞。
In the past year, I have seen The Titanic three times.
对读者而言，最重要的是〝现在完成式〞和〝过去式〞不同究竟在那里?最重要的不同在于，一旦在句子中讲一件过去发生的事，而且指定特定的时间，就一定要用〝过去式〞，而不能用〝现在完成式〞。比方说，〝我曾经看过「铁达尼号」〞，可以用现在完成式，因为这句话没有指明任何特定的时间，假如说，〝我昨天晚上去看「铁达尼号」〞，就一定用过去式，读者不妨看看以下的比较：
(a)I went to America last year.
I have been to America.
(b)I saw The Titanic last year.
I have seen The Titanic twice.
(c)I finished my homework late last night.
I have finally finished my homework.
(d)I studied English when I was a small child.
I have studied English since I was a child.
(e)I went to church yesterday.
I have never been to church.
以下的句子是错的，请特别注意：
*(1)I have seen the movie last year.
*(2)I have never been to America last year.
*(3)He has never finished his work last night.
现在完成式常和since、for、already、never、ever等字一起使用，以下都是这类的例子：
(1)I have already had dinner.
(2)Since this summer began, we have already had two storms.
(3)It has not rained for a long time.
(4)I have never talked to this man before.
(5)I have never met your father.
(6)Have you ever been to America?
(7)He has already won three awards.
(8)I have stayed here since June.
Never 和 ever 也常是我们弄不清楚如何使用的字，一般说来， never 有否定的意思，ever则只有在问句中才会出现。
