Lǐ / lǎo / shī / shì / wǒ / de / lǎo / xiāng / shí / wǒ / men / rèn / shi / yǐ / jīng / èr / shí / duō / nián / le

李老师是我的老相识，我们认识已经二十多年了。

Teacher Li is an old acquaintance of mine; we have known each other for over twenty years.