It has taken several months to get there为什么不直接说It took?

问题描述:

It has taken several months to get there为什么不直接说It took?
I heard they have gone to Shanghai on business 为什么前面不说I have heard?

have done 现在完成时表过去发生的动作并且其本身或影响持续到现在并可能持续到将来
took/heard 是一般过去时,表示动作在过去的某个时间点上发生,没有包含持续的意义