有没有it was +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? 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 was +since 为什么有It was over但没有It was ended It is /was +时间+ since… 其中is has been was had been.与强调句的区别 It is+时间段+since+时间点 It is+段时间+since sb did. It is+时间段+since+时间点. it is ...since it was...before 一定是过去式吗? It's weeks since I was ill.It's weeks since I fell ill. 什么时候用It was+一段时间 +since,什么时候用It is +一段时间+since? 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