一般过去时现在完成时主要用于:
1 、表示到现在为止这一时期中发生的动作或情况,即多次动作的总和。
e.g. We have learnt four English songs this month.
How many times have you read the novel?
For many days we haven`t seen each other.
2 、表示对现在有影响的某一已发生的动作。
e.g. The delegation has left 代表团已经走了(说明现在不在这里)
Look, what you have done. 看你干的事。
与这一时态连用的时间状语有:
already, yet, just, ever, never, by now, so far, recently, by the end of this month, since, for 短语,连词 since 引导的时间状语从句。