解释一下该句子的时态Since he came here last year, we have been happy.解释一下主句和从句之间时态的判断.

解释一下该句子的时态Since he came here last year, we have been happy.解释一下主句和从句之间时态的判断. 41.My brother left school in 2005,and since then he ________ in Beijing.A.lived B.had livedc.has lived为什么选C,不是since前面的句子才用完成时态么?后面应该用过去时态呀,而且前面是过去时态,后面从句的时态也应 加since的句子时态的用法句子后面+since,前面的时态应该用什么.比如 I___here since I was a child.A.have been staying B.had been staying C.stayed D.have stayed E.had stayed 在现在完成时态 since 引导的句子中,主句的谓语动词必须用持续动词吗?He has left here since two years ago.He has been away since two years ago.是两个都对,还是有错? 用正确的时态改写句子：例句：He __has gone___ to Silbury yesterday.改动以后：He went to Silbury yesterday.1.She ___was__ abroad since last January. 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? 关于完成时态的!He said that he had met her two years.A.before B.ago C.for 2 years D.since 2 years ago since前后该用什么时态啊? since和for的区别时态时态! Since then he was been doing the work.怎么译?用的是什么时态? 谁能帮我全面的解释一下since这个词像什么是since前后时态不一样,若是延续性动词则前后相反,瞬间性动词则前后一致,最好有例子 关于since 和 by 的时态since 是不是一定会跟完成时态的的句子?那by 是不是一定是过去完成时呢? 如果主句是现在完成时态,那么回答它的句子如果有since,那么since后接什么时态,为什么 since引导的句子主句和从句分别用什么时态? ever since用作副词,放于句末时句子的时态可以是什么? ever since 和since 还有since then 有什么区别?它们分别用在什么时态..在句子的哪个位置?怎么用? since引导的从句时态,求问i haven't heard from him since he lived in shanghai和i didn't hear from him since he lived in shanghai哪一句时态是对的?since引导的从句时态与主句时态求问（注：那一句是主句那一句是从 ever since 的用法ever since 和什么时态连用?