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主题：
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gfddh |
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内容：
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1.什么叫现在完成时？ |
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提交人：
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张予琪
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时间：
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5/27/2002 13:55:36
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主题：
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answer English |
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内容：
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现在完成时的构成
现在完成时由”助动词have(has)+过去
分词”构成。现以work为例，将现在完成时的肯定式、否定式和疑问式以及简略答语列表如下：
肯定式 否定式
I/You have worked．He/She/It has worked．We/You/They have worked． I/You have not(haven''t)worked．He/She/It has not(hasn''t)worked．We/You/They have not(haven''t)worked．
疑问式和简略回答
Have I/you worked?Has/he/she/it worked?Have we/you/they/worked? Yes，you/I have．Yes，He/she/it has．Yes，you/we/they have． No, you/I have not(haven''t)．No，he/she/it has not (hasn''t)．No，you/we/they have not(haven''t)．
规则动词的过去分词构成与动词过去式相同，不规则动词的过去分词见本章末《不规则动词表》。have not常略为haven''t[''hAvnt]，has not 常略为hasn''t[hAznt]．
2。现在完成时的用法。
（1）表示过去发生或已经完成的某一动作对现在造成的影响或结果，常与already，just，yet，ever，never等连用。例如：
Have you finished your work yet？
Yes，I have．I have just finished it．
I have already finished it．
No，I haven''t finished it yet．
Have you ever been to a chicken farm？
Yes，I have．
No，I have never been to a chicken farm．
（2）表示过去已经开始，持续到现在的动作或状态，可以和表示从过去某一时刻延续到现在（包括”现在”在内）的一段时间的状语连用。如：for，since，now，today，this month，this year等。例如：
I have known Li Lei for three years．
I have lived here since 1980．
I have been at this school for over fourteen years．
for和表示一段时间的词组连用。例如：for two minutes，for five hours，for ten days，for three weeks，for fourteen months，for twenty years．
since和表示过去某一时刻的词或词组连用。例如：since eight o''clock this morning，since last Sunday，since five weeks ago，since October等等。We have planted many trees this year．My mother has made many cakes today．但如果说话人所感兴趣的只是在这段时间内发生了某一动作，而不是这一动作与现在的关系时，须用过去时态。例如：
Our school built a new building this year．
（3）have(has)been和have(has)gone的区别：表示”曾到过某地”，要用have(has)been，不能用have(has)gone．例如：
Where has he been？他刚才到哪儿去了？
（他已回来了。）
Where has he gone？他到哪儿去了？
（他现在不在这里。）
She has been to Shanghai．她到上海去了。
（她可能在去上海的路上或已到上海，总之现在不在这里。）
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提交人：
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tchwusk
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时间：
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5/27/2002 13:55:53
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