小学六年级英语语法

Since用来说明动作起始时间，for用来说明动作延续时间长度。

Ihavelivedhereformorethantwentyyears.

IhavelivedheresinceIwasborn..

Myaunthasworkedinaclinicsince1949.

Somenewoilfieldshavebeenopenedupsince1976.

IhaveknownXiaoLisinceshewasalittlegirl.

MybrotherhasbeenintheYouthLeaguefortwoyears.

Ihavenotheardfrommyuncleforalongtime.

注意：并非有for作为时间状语的句子都用现在完成时。

Iworkedhereformorethantwentyyears.

(我现在已不在这里工作。)

Ihaveworkedhereformanyyears.

(现在我仍在这里工作。)

小窍门： 当现在完成时+一段时间，这一结构中，我们用下面的`公式转化，很容易就能排除非延续动词在完成时中的误使。

1) (对)TomhasstudiedRussianforthreeyears.

=TombegantostudyRussianthreeyearsago,andisstillstudyingitnow.

2) (错)Harryhasgotmarriedforsixyears.

=Harrybegantogetmarriedsixyearsago,andisstillgettingmarriednow.

显然，第二句不对，它应改为Harrygotmarriedsixyearsago. 或Harryhasbeenmarriedforsixyears.