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?

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? 有没有it is been+段时间+since和it was be+段时间+before这种表达? 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 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 为什么有It was over但没有It was ended 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 请教大家一个英语语法问题 3Q有这么一个句型 It is/has been ... since +一般过去式 若是It was/had been ...since+... since后应该加过去完成时还是一般过去式我认为加了一般过去式两个事件的时间就 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 英语翻译她离开班级已有三年。这好像是关于since的语法 例如：it was three years since he smoked a cigar==it was three years since he stoped to smoke cigar it is ...since it was...before 一定是过去式吗? it was waiting for Tom_he was doing homework用since 还是while 答案是since, 分析这个英语句子的时态和句意!it is／was 3 years since he came here.since不一定和完成时连用吗?用is或was有什么区别 为什么since不能用做that? It's been a while since I left here 这个here 到底有没有问题啊 什么时候用It was+一段时间 +since,什么时候用It is +一段时间+since? it is ...since ..为什么不用完成时it is 100 years since Qinghua university was found. It is 一段时间 since.这句型中is可以换成was或其他什么时态吗?有什么区别. It has been ten years since he was a teacher.这句话有什么错误?可以怎么改? It was ten years since I left my hometown.改错