it's...since的用法比如since后跟结束性动词是什么意识,跟延续性动词是什么意思

it's...since的用法比如since后跟结束性动词是什么意识,跟延续性动词是什么意思 it is+时间段+since的用法 当主句有last该怎么办,和时间段+since的用法一样么?这里有三道题It's a long time since we___(meet)last year.It's a long time since we___(meet)last,isn't it?More than 15 years ___(pass)sin It's years since I enjoyed myself so much.其中since是什么用法? it has been since.用法 it's +时间+since/that/when/before句型用法的差别它们分别有什么条件吗? since后加现在完成时和一般过去时的区别比如It's three years since he has worked there.和It's three years since he worked there.有什么区别 It looks as if从句和“It's 3 years since 从句”两句的的IT的含义和用法?请问下面这两个IT的含义和用法?1 It's 3 years since 从句；2 It look as if从句.如果是形式主语,也不对啊,SINCE和AS IF引导的都不是 It's nothing的用法~ It's taken.的用法 since的用法 since的用法 since 的用法 since的用法是什么? since的各种用法 介词 since 的用法? 请问下面这两个IT的含义和用法?1 It's 3 years since 从句；2 It look as if从句.如果是形式主语,也不对啊,SINCE和AS IF引导的都不是主语从句, i think it's been a long time since i've heard anyone is good since在这里是什么用法? It's的用法比如It's up to you.由你决定为什么没有决定这词It's 可以代替哪些词啊