时态比较

We have learned so many things from you so far.
I have seen any bird like this in my life.

6．对过去的体验和经历。
常用的时间状语有：before, ever, once, twice, many times
注意：这两句话的区别
I have been to Beijing （去过北京）
I have gone to Beijing（去北京了，人还没回来〕
Have you seen tiger before?
I have been to Shanghai many times.

从上面几方面的分析， 我们把现在完成的用法和时间状语联系起来一起考虑，掌握完成时态的用法。