一般过去时标志:ago,yesterday,the day before yesterday,last year/month/night...,in 1989,just now。现在完成时标志:already,yet,just,before,recently,still,lately。
现在完成时的用法1.表示过去发生并且已经完成的动作对现在的影响及产生的结果
2.肯定句:主语+have+过去分词、主语(第三人称单数)十has+过去分词
3.否定句:主语+ have not+过去分词、主语(第三人称单数)+ has not+过去分词
4.疑问句:Have+主语十过去分词、Has+主语(第三人称单数)+过去分词
5.用法
[1]完成时的这种用法通常与由since或for引导的时间状语连用。如:
The old man has lived here for more than twenty years.
老人已在此住了20多年了。
完成时的这种用法有时不带时间状语,有时可以和already,before,ever,just,lately,never,once,recently,yet等一些所指时间不具体的时间状语连用。如:
Have you ever been to Australia? 你去过澳大利亚吗?
[2] 有时完成时和now,today,this morning,this week,this year等的时间状语连用。如:
I haven t seen him today. 我今天没见过他。
I have seen him only once this year. 我只见过他一次。
(3)完成时在时间和条件状语从句中表示将来完成的动作
Ill go to the party as soon as (or when) I have finished my homework.
我完成作业后就去参加聚会。
(4)完成时和until now,so far,in the past few years,up to the present等表示从某时到这段时间的状语连用 I have not heard from her so far. 到目前为止,我没有收到过她的信。
We have learned five hundred words up to the present.到目前为止,我们已学了五百个生词。