He left six years ago and has not been since.

他离开六年迄今未为人所见。

He was then treasurer, but has since been elected president.

那时他掌管财务，但随即被选为董事长。

not long since

不久以前。

I have eaten nothing since yesterday.

从昨天以来，我未曾进食。

Since that time, I have never seen him.

此后我未曾遇到他。

It is two years since my father died.

自从父亲去世，已过了二年。

I have never seen him since that happened.

次事后我未见到他。

What have you done since we parted?

自我们分开后，你作些什么？

Since that is the case, I shall go.

既然如此，我要走了。