I'm going to see an old schoolmate of mine.

　　我去見一個老校友。

　　My father still keeps in touch with his old schoolmate.

　　我父親仍和他的老同學保持聯系。

　　He started the magazine with a schoolmate

　　他和一個同學創辦了那份雜志。

　　On my graduate student's time, an schoolmate's paper discussed this topic.

　　我上研究生的時候一個同學論文就是做的這個題目。

　　10 years after graduation, he could hardly recognize his old schoolmate.

　　畢業10年后，他幾乎認不出他以前的同學了。