1 sentence

1. 他们两个私下里经常做一些见不得人的勾当。

   tā​men liǎng gè sī​xià​lǐ jīng​cháng zuò yī​xiē jiàn​bu​dé​rén de gòu dàng.

   The two of them often engage in shady dealings in private.

   Source: Dong Chinese Dictionary