1 sentence

1. 他之所以这么做，其实是有难言的苦衷。

   tā zhī​suǒ​yǐ zhè​me zuò, qí​shí shì yǒu nán​yán de kǔ​zhōng.

   The reason he did this was actually because he had some unspeakable difficulties.

   Source: Dong Chinese Dictionary