3 sentences

1. 敌军对该城市进行了长达数小时的轰炸。

   dí​jūn duì gāi chéng​shì jìn​xíng le cháng​dá shù xiǎo​shí de hōng​zhà.

   The enemy bombarded the city for several hours.

   Source: Dong Chinese Dictionary

2. 他痴迷于古典文学，每天都要花数小时阅读。

   tā chī​mí yú gǔ​diǎn wén​xué, měi tiān dōu yào huā shù xiǎo​shí yuè​dú.

   He is obsessed with classical literature and spends hours reading it every day.

   Source: Dong Chinese Dictionary

3. 经过长达数小时的激烈比赛，他已感到体力已弊，难以为继。

   jīng​guò cháng​dá shù xiǎo​shí de jī​liè bǐ​sài, tā yǐ gǎn​dào tǐ​lì yǐ bì, nán​yǐ​wéi​jì.

   After several hours of intense competition, he felt physically exhausted and found it difficult to keep going.

   Source: Dong Chinese Dictionary