现在完成时用法持续性用法现在完成时用法持续性用法持续性用法（肯定句，疑问句中谓语动词必须是延续性动词）：表示过去已经开始，持续到现在的动作或状态。此时常与“for一段时间或“since过去的点时间或从句（从句用一般过去时）以及so far（到目前为止）等时间状语连用。for +段时间since +点时间实例：1）Ive lived here since 1990自从1990年以来我就住在这里。 = Ive lived here since 13 years ago.= Ive lived here for 13 years. = It is 13 years since I began to live here.2）I havent seen him for three years我三年没有看见他了。 = I havent seen him since three years ago. = It is 3 years since I saw him last time.3）Mr W
