2 sentences

1. 有时候你真的很难懂。

   yǒu​shí​hou nǐ zhēn​de hěn nán dǒng.

   Sometimes you really are hard to understand.

   Source: OpenSubtitles

2. 这本书深奥难懂，我花了一周才卒读。

   zhè běn shū shēn'ào nán dǒng, wǒ huā le yī zhōu cái zú dú.

   This book is so profound and difficult that it took me a week to finish reading it.

   Source: Dong Chinese Dictionary