(already, yet, just, since, for)

Would you like something to eat? 要不要吃点什么？

No, thanks. I have already had my breakfast.

谢谢，我已经吃过早餐了。

No, thanks. I have had my breakfast already.

No, thanks. I have just had my breakfast. 谢谢，我刚刚吃过早餐。

Thanks. I haven't had my breakfast yet. 谢谢，我还没吃早餐呢。

Thanks. I haven't eaten anything since last night.

谢谢，从昨晚到现在我什么都没吃呢。

I have known him since he was a boy.

我从他还是小孩的时候就认识他了。

We have known each other for over 20 years. 我们认识超过20年了。