had been,has been,has,had 后面加过去分词都是怎么用的?
问题描述：
had been,has been,has,had 后面加过去分词都是怎么用的?
【以及和was,is有什么区别?】
答
首先is和was 在现在时态用is过去事态用washad been /(pp)是过去完成事态的用法.一般用在时间方面,如：It had been for 3 years since he left I had finished it yesterday.has been/(pp) p.s.pp 是过去分词是一...