Question

It is ten years since he smoked or didn't smoke

该题意思是不吸烟了以有十年可我不会解释

Answer 1

It is ten years since he didn't smoke
他不抽烟已经有10年了
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对于楼上，完成式的说法——我不同意！
虽然这里用了since，
但是不需要用完成式！

Answer 2

一般这种情况用现在完成时表示．

It has been ten years since he didn't smoke.

因为since是完成时专用的，自从他不吸烟这个时间点开始算，至今已经十年了．

Answer 3

It is ten years since he smoked
他已经抽烟有10年了
如果加上or didn't smoke
语法就有错误了

反正就是有问题

Answer 4

It is ten years since he smoked 自从他吸烟已10年了。