It+be+时间段+since,before....句型

It + be + 时间段 + since / before 句型句型意义备注It will/wont be+ 时间段+before要等多长时间才/过不了多长时间就It was/ wasnt + 时间段 +before过了多长时间才/没过多长时间就It is/has been + 时间段 +since自从以来已经有多长时间了1.从句中用短暂性动词表示动作持续了多久2.从句中用延续性动词表示动作结束了多久3.从句要用一般过去时It will be two years before he comes back from abroad. 要等两年他才回国。It wont be two years before he comes back from abroad. 过不了两年他就回国。It was two years before he came back from abroad. 过了两年他才回国。It wasnt two years before he came back from abroad. 没到两年他就回国了。It is/has been two years since he came back from abroad. 他回国已经两年了。It is/has been two years since he lived abroad. 他不在国外已两年了。n How long do you think it is _ he arrived here?- No more than half a year, I believe.n It was two years later _ he came back from abroad.n It is two hours _ he spends on English every day.n It was at 6 oclock _I got up today.n It was 6 oclock _ I got up today. 1. It is / was (high / about) time +(that) “是做的时候了”，从句的谓语动词用： 过去式（be用were） should+ 动词原形，should 不可省, 表示虚拟语气。It is time that he came back from abroad. 他早该回国了。2. It + is + the first / second time + that It is the first time that I have visited the Great Wall.3. It + was + the first / second time + thatIt was the first time that I had visited the Great Wall.4. It + be + 时间点 + when 引导的时间状语从句It will be tomorrow morning when we leave for