Since 用來(lái)說(shuō)明動(dòng)作起始時(shí)間，for用來(lái)說(shuō)明動(dòng)作延續(xù)時(shí)間長(zhǎng)度。

I have lived here for more than twenty years.

I have lived here since I was born..

My aunt has worked in a clinic since 1949.

Some new oilfields have been opened up since 1976.

I have known Xiao Li since she was a little girl.

My brother has been in the Youth League for two years.

I have not heard from my uncle for a long time.

注意：并非有for 作為時(shí)間狀語(yǔ)的句子都用現(xiàn)在完成時(shí)。

I worked here for more than twenty years.

(我現(xiàn)在已不在這里工作。)

I have worked here for many years.

(現(xiàn)在我仍在這里工作。)

小竅門：當(dāng)現(xiàn)在完成時(shí)+一段時(shí)間，這一結(jié)構(gòu)中，我們用下面的公式轉(zhuǎn)化，很容易就能排除非延續(xù)動(dòng)詞在完成時(shí)中的誤使。

1)(對(duì)) Tom has studied Russian for three years.

= Tom began to study Russian three years ago, and is still studying it now.

2)(錯(cuò)) Harry has got married for six years.

= Harry began to get married six years ago, and is still getting married now.

顯然，第二句不對(duì)，它應(yīng)改為 Harry got married six years ago.或 Harry has been married for six years.

Since 用來(lái)說(shuō)明動(dòng)作起始時(shí)間，for用來(lái)說(shuō)明動(dòng)作延續(xù)時(shí)間長(zhǎng)度。

I have lived here for more than twenty years.

I have lived here since I was born..

My aunt has worked in a clinic since 1949.

Some new oilfields have been opened up since 1976.

I have known Xiao Li since she was a little girl.

My brother has been in the Youth League for two years.

I have not heard from my uncle for a long time.

注意：并非有for 作為時(shí)間狀語(yǔ)的句子都用現(xiàn)在完成時(shí)。

I worked here for more than twenty years.

(我現(xiàn)在已不在這里工作。)

I have worked here for many years.

(現(xiàn)在我仍在這里工作。)

小竅門：當(dāng)現(xiàn)在完成時(shí)+一段時(shí)間，這一結(jié)構(gòu)中，我們用下面的公式轉(zhuǎn)化，很容易就能排除非延續(xù)動(dòng)詞在完成時(shí)中的誤使。

1)(對(duì)) Tom has studied Russian for three years.

= Tom began to study Russian three years ago, and is still studying it now.

2)(錯(cuò)) Harry has got married for six years.

= Harry began to get married six years ago, and is still getting married now.

顯然，第二句不對(duì)，它應(yīng)改為 Harry got married six years ago.或 Harry has been married for six years.