这次考试对我来说很艰难。

Zhè cì kǎoshì duì wǒ lái shuō hěn jiānnán.

This exam was very difficult for me.

他经历了一段艰难的时期。

Tā jīnglìle yīduàn jiānnán de shíqī.

He went through a difficult period.

完成这个项目的过程非常艰难。

Wánchéng zhège xiàngmù de guòchéng fēicháng jiānnán.

The process of completing this project was extremely challenging.