7 sentences

1. 我不知这件事的真相。

   wǒ bù​zhī zhè jiàn shì de zhēn​xiàng.

   I don't know the truth about this matter.

   Source: Dong Chinese Dictionary

2. 真不知该如何谢你。

   zhēn bù​zhī gāi rú​hé xiè nǐ.

   I don't know how to thank you.

   Source: OpenSubtitles

3. 在下有一事相求，不知可否请您帮个忙？

   zài xià yǒu yī shì xiāng​qiú, bù​zhī kě​fǒu qǐng nín bāng gè máng?

   I have a favor to ask. I wonder if you might be able to help me?

   Source: Dong Chinese Dictionary

4. 这个杯子的分子结构不知怎么被改变了。

   zhè​gè bēi​zi de fēn​zǐ jié​gòu bù​zhī zěn​me bèi gǎi​biàn le.

   Somehow the molecular structure of this cup has been altered.

   Source: OpenSubtitles

5. 不知不觉中，天已经黑透了。

   bù​zhī bù jué zhōng, tiān yǐ​jīng hēi tòu le.

   Before I knew it, it had become pitch dark.

   Source: Dong Chinese Dictionary

6. 两人聊得投机，不知时间已过半夜。

   liǎng rén liáo de tóu​jī, bù​zhī shí​jiān yǐ guò bàn​yè.

   The two were having such a good conversation that they didn't realize it was already past midnight.

   Source: Dong Chinese Dictionary

7. 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