5 sentences

1. 不知不觉间，三年过去了。

   bù​zhī​bù​jué jiān, sān nián guò​qù le.

   Before I knew it, three years had passed.

   Source: UM-Corpus: News

2. 不知不觉中，我到达了莫斯科。

   bù​zhī​bù​jué zhōng, wǒ dào​dá le mò​sī​kē.

   Before I knew it, I arrived in Moscow.

   Source: CCMatrix

3. 时光就在游戏中不知不觉地过去了。

   shí​guāng jiù zài yóu​xì zhōng bù​zhī​bù​jué de guò​qù le.

   Time passes unnoticed during the game.

   Source: CCMatrix

4. 不知不觉地，她发现自己在判断他的身高。

   bù​zhī​bù​jué de, tā fā​xiàn zì​jǐ zài pàn​duàn tā de shēn​gāo.

   Unconsciously, she found herself judging his height.

   Source: CCMatrix

5. 当第三个人进来时，你们会不知不觉地形成一个三角形。

   dāng dì sān ge rén jìn lai shí, nǐ​men huì bù​zhī​bù​jué de xíng chéng yī​ge sān​jiǎo​xíng.

   When a third person enters, you will unconsciously form a triangle.

   Source: CCMatrix