3 sentences

1. 他的生活非常单调。

   tā de shēng​huó fēi​cháng dān​diào.

   His life is very monotonous.

   Source: Dong Chinese Dictionary

2. 这种单调的食物我已经吃厌了。

   zhè zhǒng dān​diào de shí​wù wǒ yǐ​jīng chī yàn le.

   I'm tired of eating this monotonous food.

   Source: Dong Chinese Dictionary

3. 单调乏味的生活让他的精神逐渐枯萎。

   dān​diào fá​wèi de shēng​huó ràng tā de jīng​shén zhú​jiàn kū​wěi.

   A monotonous life caused his spirit to gradually wither away.

   Source: Dong Chinese Dictionary