tóng xué
我们自幼同学
Wǒmen zì yòu tóngxué.
We have been schoolmates since childhood.
我和他同过三年学。
Wǒ hé tā tóngguò sān nián xué.
He and I were classmates for three years.
老同学
Lǎo tóngxué
Old classmate