Section A 3Grammar focus – 4c 表示从过去已经开始持续到现在的动作或状态，可以和表示“从过去某一时刻延续到现在的一时间状语”连用，如“for+时间”、“since+过去时间点”、“since+过去时的从句”、“since+一时间+ago”。且for与since引导的时间状语可以相互转换。Present Perfect Tense现在完成时过去的动作或状态，一直持续到现在，for、since 把时间带。e.g. My uncle has worked at this factory for ten years.= My uncle has worked at this factory since ten year ago. I’ve?lived?here?since?1990． 自从1990年以来我就住在这里。?? I?haven’t?seen?him?for?three?years. 我三年没有看见他了。?? 瞬间动词的肯定式不能和时间连用。但其否定式可以和时间连用。因为，其否定式表示的是一种状态，而状态总是可以延续的。*He has come to Beijing for two years.He has been in Beijing for two years.*He has bought that book for three weeks.He has had that book for three weeks.*He has joined the Army for one and a half years.He has been in the army for one and a half years.It is two years since he came to Beijing. It is three weeks since he bought that book.It is one and a half years since he joined the Army. *His grandma has died for nine months.His grandma has been dead for nine months.It is nine months since his grandma died. 含有for，since的现在完成时的用法歌诀: 过去的动作或状态，一直持续到现在，for、since 把时间带。歌诀 非延续性动词用完成时态，在肯定句中不能与for 或 since引出的 |
