精选优质文档-倾情为你奉上英语四级考试必备基础语法知识动词时态1)现在完成进行时态 (have/has been + -ing 分词构成): 动作或状态从过去某时开始,继续到现在,可能继续下去,也可能刚刚结束.Ive been writing letters for an hour.Ive been sitting in the garden.2)过去完成进行时(由had been + ing分词构成): 过去某个时刻以前一直在进行的动作Id been working for some time when he called.We had been waiting for her for two hours by the time she came.3)将来完成进行时: 将来某个时刻以前一直在进行的动作.By next summer, he will have been working here for twenty years.In another months time shell
