2 sentences

1. 他在思索如何解决这个复杂的难题。

   tā zài sī​suǒ rú​hé jiě​jué zhè gè fù​zá de nán​tí.

   He is pondering how to solve this complex problem.

   Source: Dong Chinese Dictionary

2. 在漫长的岁月中，他苦苦思索着如何渡此余生。

   zài màn​cháng de suì​yuè zhōng, tā kǔ​kǔ sī​suǒ zhe rú​hé dù cǐ yú​shēng.

   During the long years, he pondered how to spend the rest of his life.

   Source: Dong Chinese Dictionary