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

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
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句要标明哦）

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
第一句对.
凡是句中由since引导一个时间状语从句,其主句的时态一定是现在完成时或现在完成进行时.
含有since的是从句.
since he lived in Shanghai 是从句；I haven't heard from him 是主句.

i haven't heard from him since he lived in shanghai 是对的
句中有since 一定要用现在完成时
since 引导的句子“主现从过”（主句用现在完成时，从句用过去时）
since后面的句子是从句，另一个是主句

since的四种用法
1、since +过去一个时间点（如具体的年、月、日期、钟点、1980, last month, half past six）。例如：
I have been here since 1989. 1989起，我一直在这儿。

2、since +一段时间+ ago。
例如：
I have been here since five ...

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since的四种用法
1、since +过去一个时间点（如具体的年、月、日期、钟点、1980, last month, half past six）。例如：
I have been here since 1989. 1989起，我一直在这儿。

2、since +一段时间+ ago。
例如：
I have been here since five months ago. 我在这儿，已经有五个月了。

3、since +从句。
例如：
Great changes have taken place since you left. 你走后，变化可大了。
Great changes have taken place since we were here. 我们走后，变化可大了。

以上三种情况主句全部要用现在完成时。

其中第三种用法，since+从句 又有三种情况：
1）since 后面的从句的谓语动词是一般过去时，并且这个动词是终止性的动词（比如：come、leave等等），这种情况下，从句表示的时间是“从动作开始的那一时刻起”，比如上面例句： Great changes have taken place since you left.
意思是：自从你走后，变化可大了

2）since 后面的从句的谓语动词是一般过去时，而这个动词是持续性动词或者表示状态的动词，这种情况下，从句表示的时间是“从持续动作或状态结束时算起”，比如你问题里的句子：
i haven't heard from him since he lived in shanghai.
意思是：自从他离开上海，我再也没收到过他的来信。

3）since后面的从句的谓语动词是持续性动词或者表示状态的动词的现在完成时，则表示动作或状态一直延续到现在，其表示的时间的起点是从动作发生之时算起。比如把你问题里的句子换个时态：
i haven't heard from him since he has lived in shanghai.
意思是：自从他住在上海，我就一直没收到过他的来信。

4、It is +一段时间+ since从句。例如：
It is two years since I became a postgraduate student. 我考上研究生有两年了。
这个句型和It has been+一段时间+since从句意思一样，需要注意的是：
这两个句型后面的since 从句绝不能用否定式的谓语动词来表示否定的意思。
并且第三种情况下的三种小的情况同样适用这个句型。

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