4 sentences

1. 那天正好是他的生日。

   nà​tiān zhèng​hǎo shì tā de shēng​rì.

   That day happened to be his birthday.

   Source: Dong Chinese Dictionary

2. 我那天真的不太方便。

   wǒ nà​tiān zhēn​de bù tài fāng​biàn.

   That day doesn't really work for me.

   Source: OpenSubtitles

3. 我那天在书店看见他了。

   wǒ nà​tiān zài shū​diàn kàn​jiàn tā le.

   I saw him at the bookstore that day.

   Source: Dong Chinese Dictionary

4. 你那天做了什么？

   nǐ nà​tiān zuò le shén​me?

   What did you do that day?

   Source: OpenSubtitles