It is /was +时间+ since… 其中is has been was had been.与强调句的区别不过我想知道这个结构和强调句怎么区别，还有，他们告诉我has been was 和is 没什么区别的！请再费心了

英语翻译it is/was 一段时间 +beforeit is/was 时间点 +whenit is/was 一段时间+ since 有没有it is been+段时间+since和it was be+段时间+before这种表达? 有没有it was +时间 since ...大家一定知道有It is +时间 since .请问有没有 it was +时间 since.如果有,请问it was 后面加什么?since后面加什么? as it is/was是什么意思 it was 时间when it was 时间before it was 时间since 这几个句型有什么区别 It is/was +段时间 +连词（since/before）+一般现在时,一般过去It is/was +段时间 +连词（since/before）+一般现在时,一般过去时,或完成时.请哪位懂的讲一下,关于连词的固定句型 Is it in 1949 ( ) China was liberated?A.whenB.in whichC.thatD./为什么选C? 这是不时间状语从句吗? it is cold与it was cold问What day is it回答 It is cold还是 It was cold 强调句it is（was) .that/who,其中it is（was)能不能写成it's/it was不能缩写么? It was very hot yesterday.So( ).And so ( )today.A.it was ;it is B.was it,it is C.it was,is it D.was it,is it it was(is) ...that+什么时态 It is/was time that 的用法 it is the house (　　)he was born is that right how was it? It is +段时间＋since+主语＋did.请比较：It was +段时间＋since+主语＋had done.如：It is five years since he left here.他已经离开这儿五年了.It was five years since he left here.（同上） 请问第二句不是应该用it since 3 years ago.是时间点还是时间段3 years ago.是时间点还是时间段.2.since 1985 是时间点 还是时间段?3.It is +一段时间+ since从句.怎么翻译?自从.已经多少年了》?是这样翻译吗我在网上查的说，sinc it is ...since it was...before 一定是过去式吗? It is Monday today and it was Sunday y______.