三个词引导时间状语从句时我区别.before ,until 这两个词用一般现在时表示将来时.如I will wait here until he comes back.It will be two years before he returns.当主句是过去时的时候从句也用过去时.如Yesterday...
.时间状语:yet,already,just,never,ever,so far,by now,since+时间点,for+时间段,recently, lately, in the past few years, etc. 现在完成时,基本结构:主语+have/has +p.p(过去分词)+其他 时间状语:since+时间点,for+时间段等.现在完成进行时 时间状语:Before...
不一样。 before有三种 一种是引导状语从句,要满足主将从现,如I'll go home before my mom calls me 一种是现在完成时标志,如I have been to China twice before.这时before在句尾 一种是过去完成的标志,即before+过去时间点+主句,如, before I came to Jinan...