3 sentences

1. 由于努力工作，他感到十分疲倦。

   yóu​yú nǔ​lì gōng​zuò, tā gǎn​dào shí​fēn pí​juàn.

   He felt very tired because of his hard work.

   Source: Dong Chinese Dictionary

2. 他为了完成实验，整整三天不知疲倦地工作。

   tā wèi​le wán​chéng shí​yàn, zhěng​zhěng sān tiān bù​zhī pí​juàn de gōng​zuò.

   He worked tirelessly for three whole days to complete the experiment.

   Source: Dong Chinese Dictionary

3. 经过一整天的高强度工作，他感到非常疲倦。

   jīng​guò yī zhěng​tiān de gāo qiáng​dù gōng​zuò, tā gǎn​dào fēi​cháng pí​juàn.

   After a day of high-intensity work, he felt very tired.

   Source: Dong Chinese Dictionary