since用延续性还是短暂性

都可以

1、 since后是非延续性动词，时间起点从该动作发生算起，意为“做某事多久了”

since后是延续性动词，时间起点从该动作结束算起，意为“不做某事已有多长时间”。

since引导时间状语从句的用法：

用法1：since引导的时间状语从句中用短暂性动词的过去式，主句用现在完成时或现在完成进行时。此时，整个句子可以直接按照字面意思翻译。

例句1：

She has dealt with five guys since she divorced Tom.她和汤姆离婚后和五个男人交往过。

例句2：I have been missing her since she left.自从她离开我就一直很想念她。

用法2：since引导的时间状语从句中用延续性动词或者状态动词的过去式，主句用现在完成时或者现在完成进行时。

例句1：

It has been almost five years since I taught high school students.我不教高中已经大概有五年了。

例句2:

I have changed my job five times since I was in Shanghai.我离开上海后换了五次工作。

用法3：since引导的时间状语从句中的动词用延续性动词的现在完成时，主句的动词用现在完成时或者现在完成进行时

例句1：

It has been almost five years since I have taught senior three students.我从教高三开始到现在已经五年了。

例句2：

I have never heard from her since she has worked there.自从她去那工作到现在为止，我没有收到过她的来信。

用法4：

since引导的时间状语从句中的动词用现在完成进行时，主句谓语动词用一般现在时。

例句1：

We think highly of your up-grading spirit since you have been trying to change yourself.从你一直努力改变自己以来，我们都高度赞赏你的上进精神。

例句2：

We all admire you since you have been doing everything to help the poor.

自从你一直做任何事情帮助穷人以来，我们都很钦佩你。