Question

如何区分过去完成时和现在完成时啊?

Answer 1

1. 现在完成时的动作虽发生在过去，但强调的是对现在造成的影响。
构成：have / has + 动词的过去分词
如: He has eaten the breakfast. 他已经吃过早饭了。（强调现在不饿）
He has been to Beijing twice. 他已经去过北京两次
I have lived in Beijing since I came to China. 自从我来到中国就住在北京。
I have learned French for two years 同义句 I have learned French since two years ago.
构成现在完成时的时间状语：already, ever, never, yet, so far(到目前为止）, in the past/ last few years (在过去的几年间），over the years （近年来）
2. 过去完成时动作发生在过去的过去。 He said he had been to Beijing twice. 他说他已经去过北京两次。（因为“说”said就是过去式，而去北京的动作发生在说said 的过去，所以用过完而不用现完。
过去完成时常用的时间状语有 1. by the end of last year.
By the end of last term, we had learned 5000 new words.
2. By the time sb. +动词过去式 如：The bus had already left by the time I got there.
3. 宾语从句
He went to Canada last month. 他上个月去加拿大了。
He said he had been to Canada last month. 他说他上个月去加拿大了。
主句谓语动词是过去式said , 从句谓动发生在过去的过去，所以用过去完成时

Answer 2

一>一般过去时
表示过去某段时间发生的事情,存在的状态或者过去反复发生的动作,一般有明确的过去时间状语,如:YESTERDAY
;IN
1986;LAST
YEAH等等
例:HE
WORKED
IN
A
FACTORY
IN
1986.
表示过去的状态
HE
SAW
MR.
WANG
YESTERDAY.
表示过去发生的事情
I
USED
TO
SMOKE
表示过去反复发生的动作.
你所举的例子就是描述过去事实,有表示过去时间的状语LAST
YEAR.
二>现在完成时,由HAVE/HAS+过去分词
1>表示动作在说话之前已经完成,但对现在有影响.一般没有具体时间状语
例:HE
HAS
BEEN
TO
FUZHOU.表示他去过福州,但是现在不在福州
2>现在完成时还表示动作开始于过去,并持续到现在,也许还会持续下去,常与FOR和SINCE表示一段时间的状语连用,也包括SO
FAR,NOW,TODAY,THIS
WEEK,(MONTH,YEAR)等表示包括现在的时间在内的状语.
例:NOW
I
HAVE
FINISHED
THE
WORK.
HE
HAS
STUDIED
ENGLISH
SINCE
1985.
HE
HAS
STUDIED
ENGLISH
FOR
5
YEARS.
但要注意的是短暂性动词(如:COME,GO,DIE,MARRY,BUY等)的完成时不能与FOR,SINCE等表示一段时间的词连用.
3>现在完成时还可以在时间和条件状语从句中表示将来某时完成的动作.
例:IF
IT
HAS
STOPPED
SNOWING
IN
THE
MORNING,WE'LL
GO
TO
THE
PARK.

I'LL
GO
TO
YOUR
HOME
WHEN
I
HAVE
FINISHED
MY
HOMEWORK.
三>过去完成时,HAD+过去分词,即过去的过去
1>表示在过去某一时刻或者某一动作之前完成的动作或状态.句中常用BY,BEFORE,UNTIL,WHEN等词引导的时间状语.
例:I
HAD
LEARNT
5000
WORDS
BEFORE
I
ENTERED
THE
UNIVERSITY.

BY
THE
END
OF
LAST
YEAR
WE
HAD
BULIT
FIVE
NEW
HOUSES.
2>还可以表示过去某一时刻之前发生的动作或者状态持续到过去某个时间或持续下去.
例:BEFORE
THE
SLEPT,HE
HAD
WORKED
FOR
12
HOURS.
你所举的例子仅仅只是一个陈述过去事实的句子,有明显的过去时间状语,所以用过去时.而并不能表示过去某个时刻前发生的动作与状态,故不用过去完成时