(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.
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.
I have known him since he was a boy.
We have known each other for over 20 years. 我们认识超过20年了。内容来自 听力课堂网：http://www.tingclass.net/show-5855-18794-1.html