2 sentences

1. 关于这起事故的起因，有关部门正在深究。

   guān​yú zhè qǐ shì​gù de qǐ​yīn, yǒu​guān bù​mén zhèng​zài shēn jiū.

   Relevant departments are conducting an in-depth investigation into the cause of this accident.

   Source: Dong Chinese Dictionary

2. 凡事若不究其本原，很难从根本上解决问题。

   fán shì ruò bù jiū qí běn yuán, hěn nán cóng gēn​běn shàng jiě​jué wèn​tí.

   If you don't look into the root cause of a matter, it's hard to solve the problem fundamentally.

   Source: Dong Chinese Dictionary