精选优质文档-倾情为你奉上八年级下册人教版最新第八单元知识点及课后练习现在完成时讲解 现在完成时可以用来表示发生在过去某一时刻的,持续到现在的动作（用行为动词表示）或状态（be动词表示）常与for（+时间段）,since（+时间点或过去时的句子）连用.for+时间段 Mary has been illsince+过去一个时间点（译为：自从以来）I have lived here since 1998. since+时间段+ago I have lived here since six years ago.since+从句（过去时） I have lived here since I was born.It is+时段+since+从句（过去时）Its since I lived here.瞬间动词（buy,die,join,come，go ,leave,join ）不能直接与for since 连用。要改变动词buy-have; borrow -keep; come/arrive/reach/get to-
