基本形式：have/has+done（过去分词） 标志词和标志短语很多的 你不用一个个记 看一看就行了： already（肯定）, yet（否定，疑问）, just, before, recently,still, lately,never,ever,twice, on several occasion,in the pastfew days/weeks/months/years,(up to)these few days/weeks/months/years,this morning/week/month/year, up to present, so far,up to now,up till now,till now,since+点时间，for+段时间，since+段时间+ago，since+从句(过去时），It is+时段+since+从句（过去时）。
since+ 时间点, for+时间段, already, yet, ever, never, so far, until now, up to now, recently,t hese days/weeks/years,always, in the last/past( few years) 这些词出现时常用现在完成时。也不是特别绝对。 现在完成时用于 1 表示过去发生的某一动作对现在造成的结果或影响 2也可指过去开始延续到现在的动作或状态 She has worked at this school for 6 years. (过去到现在 3. 某人曾有过或到至今未有的经历 Have you ever been to the Summar Palace?
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