关于初二英语 现在完成时它和一般过去时有什么区别?最好有例题.

比较过去时与现在完成时
1）过去时表示过去某时发生的动作或单纯叙述过去的事情,强调动作；现在完成时为过去发生的,强调过去的事情对现在的影响,强调的是影响.
2）过去时常与具体的时间状语连用,而现在完成时通常与模糊的时间状语连用,或无时间状语.
一般过去时的时间状语:
yesterday,last week,…ago,in1980,in October,just now,具体的时间状语
共同的时间状语:
this morning,tonight,this April,now,once,before,already,recently,lately
现在完成时的时间状语
for,since,so far,ever,never,just,yet,till / until,up to now,in past years,always,
不确定的时间状语
3）现在完成时可表示持续到现在的动作或状态,动词一般是延续性的,如live,teach,learn,work,study,know.
过去时常用的非持续性动词有come,go,leave,start,die,finish,become,get married等.
举例：
I saw this film yesterday.
（强调看的动作发生过了.）
I have seen this film.
（强调对现在的影响,电影的内容已经知道了.）
Why did you get up so early?
（强调起床的动作已发生过了.）
Who hasn't handed in his paper?
（强调有卷子,可能为不公平竞争.）
She has returned from Paris.
她已从巴黎回来了.
She returned yesterday.
她是昨天回来了.
He has been in the League for three years.
(在团内的状态可延续)
He has been a League member for three years.
(是团员的状态可持续)
He joined the League three years ago.
( 三年前入团,joined为短暂行为.)
I have finished my homework now.
---Will somebody go and get Dr.White?
---He's already been sent for.
句子中如有过去时的时间副词（如 yesterday,last,week,in 1960）时,不能使用现在完成时,要用过去时.
（错）Tom has written a letter to his parents last night.
（对）Tom wrote a letter to his parents last night.

现在完成时表示事情发生在过去
强调对现在的影响
一般现在时 是表示发生在现在

现在完成时是由have+been结构一般过去式是由名词后+ed(通常)

现在完成时强调这一动作与现在的关系，而一般过去时只表示过去的事实。
如：I cleaned my room yesterday.我昨天打扫了房间。
I have cleaned my room now.我刚刚打扫过房间。

I went swimming yesterday 一般过去时，强调事情已经过去了
现在完成时则强调对现在的影响，并且在时间概念上与现在更紧密
如：I have finished my homework so that I can playing football

现在完成时表示事情发生在过去
强调对现在的影响
如:When you were playing basketball,I were doing homework.And I have finished it now,I can also play basketball and do what I wanted (过去时）to do.最简单的，仅仅如此，自己体会吧

现在完成时强调过去的行为对现在造成的结果，
一般过去时只是在过去发生的行为或结果。
如：I have been in Qingdao for two years since i left my hometown .现在完成时
过去的行为 left 对现在的结果是been in Qingdao for two years
I left my hometown two ...