for用来说明动作延续时间长度— “长达……” 

I have lived here for more than twenty years. 

I have lived here since I was born. 

My aunt has worked in a company since 1949. 

I have not heard from my uncle for a long time. 

注意：并非有for 作为时间状语的句子都用现在完成时：

I worked here for more than twenty years. (我现在已不在这里工作)

I have worked here for many years. (现在我仍在这里工作)

为什么 I have lived here for more than twenty years. 这句是正确的呢？live是短暂性动词，后边还跟for引导的时间状语？

并非有 for 作为时间状语的句子都用现在完成时:

I worked here for more than twenty years. (我现在已不在这里工作)

I have worked here for many years. (现在我仍在这里工作)

这句话又怎么理解? 谢谢!