熟识

zhè xiē xué yuán shú shi shuǐ xìng

这些学员熟识水性。

These trainees are expert swimmers.

wǒ men jiāo wǎng bù duō bù dà shú shi

我们交往不多，不大熟识。

We haven't met often and don't know each other very well.

bǐ cǐ shú shi

彼此熟识

know each other well

hù xiāng shú shi

互相熟识

be intimately acquainted with each other

wǒ men hé tā hěn shú shi jué de tā jī hū jiù shì wǒ jiā de yī yuán

我们和她很熟识，觉得她几乎就是我家的一员。

We all knew her so well that we felt she was almost part of the family.