文档介绍：一般现在时与现在完成时的区别
一般过去时的构成
概念:过去某个时间里发生的动作或状态;过去习惯性、经常性的动作、行为。
基本构成:主语+动词(包括be)的过去时
常用的时间状语:yesterday, last week, an hour ago, the other day, in 1982等具体时间状语。
【注】不论是否定句还是一般疑问句,只要用了助动词,原句中的谓语动词的过去时都要还原成动词原形;主+系+表结构的句子,主语要和was和were在人称和数上保持一致。
一般过去时的用法
表示过去某一时刻或某段时间发生的动作或者存在的状态。常与表示过去的时间状语连用。例如:I lived here 5 years ago.
表示在过去一段时间内,经常性或习惯性的动作。例如: When I was a child, I often played football in the street.
一般过去时的形式有时并不表示过去的动作而是只表示说话人的委婉语气。例如:could you tell me your name?
现在完成时的构成
概念:过去发生或已经完成的动作对现在造成的影响或结果,或从过去已经开始,持续到现在的动作或状态。
基本结构:主语+have/has+过去分词
否定形式:主语+have/has+not+过去分词
常用的时间状语:now,today, tonight, this week, this year, already, yet, just, since, recently,in the past few years等等
for和since的运用for表“经历(一段时间)”,而since表“自从…… 以来”。
例如:
1. He has stayed here for 3 hours.
2. He has stayed here since 3 hours ago.3. He has stayed here since 3 o’clock.
 has taught English since he came here.
Fill in the blanks with “for” or “since”:
We have had the puter _______ a week.
How long have you studied English?
I have studied English _______ I was five.
3. How long has he taught in this school?
He has taught in this school ______ 1998.
4. How long have you known each other?
We have known each other ______ over ten years.
5. How long have you kept your pet dog?
I have kept it ______ two years ago.
I have kept it ______ two years.
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James has been in Canada ______ Monday.
James has been in Canada ______ four days.
James came to Canada four days _____.
My aunt has lived in Brazil _____ 15 years.
My aunt moved to Brazil 15 years _____.
She has lived in Brazil ______ 15 years ______.
Mike has been in hospital _______ October.
Mike has been in hospital ______ two months
Mike came to the hospital two months ______
He has been in hospital ______ two months ___
填上since ,for或者ago.
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already和yet 的区别already常用于肯定句中或句末;yet常用于一般疑问句或否定句末。但表惊讶时already也可用于疑问句。例如:
 has already finishe