点头之交

wǒ hé tā jǐn yǒu diǎn tóu zhī jiāo

我和他仅有点头之交。

I have only a nodding acquaintance with him.

tā men de diǎn tóu zhī jiāo fā zhǎn chéng yǒu yì

他们的点头之交发展成友谊。

Their acquaintance ripened into friendship.

wǒ zài chéng li yù jiàn gè yǒu diǎn tóu zhī jiāo de rén

我在城里遇见个有点头之交的人。

I bumped into a casual acquaintance in town.