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什么是現(xiàn)在完成時呢?現(xiàn)在完成時用于發(fā)生在過去但現(xiàn)在仍起作用或仍是事實的情況。(The present perfect tense is used for actions that started in the past but continue into the present, or remain true in the present.)現(xiàn)在完成時是1條腿在過去,1條在現(xiàn)在,如下圖所示:

比如這個例句:

The Millers HAVE LIVED in a hut for three days.?這個句子表示the Millers在小屋里已經(jīng)住了3天了,而現(xiàn)在他們住在這個小屋,依然是事實。

和這個句子對比下:

The Millers LIVED in a hut for three days.這句表示的是the Millers在小屋里住了3天,而且他們現(xiàn)在已經(jīng)不再小屋里住了。

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現(xiàn)在完成時的組成:have/has + 過去分詞

看下面2個例子

例1: This country HAS ENFORCED strict immigration laws for thirty years.

例2: They HAVE KNOWN each other since 1987.

第一句的意思是:這個國家過去實行了嚴格的移民法案,并且現(xiàn)在還在執(zhí)行。第二句的意思是:他們從1987年就認識了對方,而且現(xiàn)在還有來往。而且這兩個句子都有時間標志詞:for thirty years和since 1987。

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還有一種情況,就是這個動作實際已經(jīng)結(jié)束了,但是它的影響還在,看下面的例子

例1: The child HAS DRAWN a square in the sand.?(小孩已經(jīng)畫完了方框,但是現(xiàn)在方框在還沙灘上,也就是畫的動作的影響還在)

再看下面2個例子

例2:The child DREW a square in the sand, but the ocean ERASED it.?(方框被海沖走,消失了,用一般過去時)

例3:The child DREW a square in the sand, but the ocean HAS ERASED it.?(方框被海沖走,沖走的影響還在)

看這個錯誤例子: The child HAS DRAWN a square in the sand, but the ocean HAS ERASED it.既然海都已經(jīng)把方框沖走了,那么畫這個動作的影響已經(jīng)不在了,所以draw不能用現(xiàn)在完成時。

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  • 現(xiàn)在完成時標志持續(xù)的動作或結(jié)束的動作仍然有作用。

當(dāng)since+過去的時間點時,要用現(xiàn)在完成時來表示這個動作的作用還在,看下面的3個例子體會下

Wrong: Since 1986, no one BROKE that world record.

Wrong: Since 1986, no one BREAKS that world record.

Right: Since 1986, no one HAS BROKEN that world record.

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與since的道理一樣,with the past和in the last(如within the past five minutes?和?in the last ten days)要用現(xiàn)在完成時表示動作還有影響。但是,當(dāng)時間短語中不包括現(xiàn)在的話(如last month和in 2007)時,這只是單純的一般過去時,所以不要用現(xiàn)在完成時??聪旅娴?個句子

Wrong: Veronica HAS TRAVELED all over the world?in 2007.

Right: Veronica TRAVELED all over the world?in 2007.

Right: Veronica HAS TRAVELED all over the world in the last five years.

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有時,為了使動詞的時間序列更加清楚,句子會使用現(xiàn)在完成時。像when有兩個意思:同時(at the same time)和以后(after),在有when的句子里,現(xiàn)在完成時有時可以明確語意??聪旅娴膬蓚€句子

例1: She WILL PAY you when you ASK her. (No present perfect沒有用現(xiàn)在完成時)

? ?? ?? ? = She will pay you at the same time as you ask her, or maybe just after.

例2: She WILL PAY you when you HAVE TAKEN out the garbage. (present perfect用現(xiàn)在完成時)

? ?? ?? ? = She will pay you after you take out the garbage.