问题 求解分析下面几组句子，请给出一个合理的时态解释。

...sp;had done + since: since前面的句子可以采用过去完成时态had done：Since the party she had only spoken to him once.（那次派对之后，她只和他说过一次话。）B. was + since + had done:since后边的从句也可以用过...

问题 It...since...主从句时态问题，以及since从句可否使用“否定式”？

...否改为It is a while since we were not out  ?  就是主从句时态改变一下，和原句意思一样吗？

问题 关于since从句的时态问题

I have had these impulses since I can remember.1.为何since从句不用since I have been able to remember?2. 如果从句用since I have been able to remember，和原句相比，二者在句意上有何细微差异？期待各位老师的帮助，十分感谢。

问题 since时态问题

I have lived here for several years now and I've made many new friends since I have lived here.请问，为什么since部分用现在完成时，而不是用过去时呢？ “自从我住在这里” 这动作不是发生在过去吗？

话题 since从句与完成时态

问题 since做连词引导句子的时态问题

...nce引导状语从句是现在完成时的话，主句一般可以有什么时态？2、上句的So much做主语是属于什么情况？感谢老师回答

问题 since主句的时态

...是不是应该用过去完成时（后句allowed)？但却用了一般过时态。再如有一个句子是：It was the worst flood since records began.这是有记录以来最严重的水灾。（牛津）

问题 since主句时态

...现在完成时对吗？老师能否给总结下主句从句都能用哪些时态？

问题 现在完成时态+since we were at college，since从什么时间算起？

We have known each other since I was at college.We have known each other since we were at college.请问这两句话since从句的起算时间一样吗？从什么时候算起？

问题 这个since的主句为什么不用完成时态？

当since表示“自从”时，它的主句谓语总是要用完成时态的，但是下面这句中，主句却用了现在进行时，请问这是为什么？House prices are rising for the first time since November. 房价自 11 月以来首次上涨。

问题 since从句不同时态产生的语义差别辨析？

关于-ing分词分句与限定从属分句的转换关系（章振邦新编高级英语语法543页。）Since being in the army, he has been in much better health.=Since he was=Since he has been请教老师，以上果真是相同的意思吗？我在薄冰英语惯用法词典945页看到：since...

问题 since引导时间状语从句时主句可以不用完成时态吗

有个问题一直让我困惑，那就是：since引导时间状语从句时主句可以不用完成时态吗？

问题 since后面能跟瞬间动词的完成时态吗？

比如 it has been 10 years since they (have) left. It is 3 years since they have seen/saw each other.

问题 It is...since...的主句与从句时态

It was three years since Jack had been a teacher.It is three years since Jack was a teacher.请问这两句有什么区别吗？分别是什么意思？第二句为什么不用has been呢？

问题 时态问题(涉及since的主句用现在进行时)

You are looking much younger since I saw you two years ago. 这句中 are looking 是不是应该改为 have looked 才正确，我记得从句用 since, 主句用完成时，对吗？