4 sentences

1. 你老板是怎么一回事？

   nǐ lǎo​bǎn shì zěn​me yī​huí​shì?

   What's up with your boss?

   Source: OpenSubtitles

2. 理论是一回事，实践又是另一回事。

   lǐ​lùn shì yī​huí​shì, shí​jiàn yòu shì lìng yī​huí​shì.

   Theory is one thing, practice is another.

   Source: Dong Chinese Dictionary

3. 那个包包是怎么一回事？

   nà gè bāo​bāo shì zěn​me yī​huí​shì?

   What's with that bag?

   Source: OpenSubtitles

4. 这两件案子其实是一回事。

   zhè liǎng jiàn àn​zi qí​shí shì yī​huí​shì.

   These two cases are actually the same thing.

   Source: Dong Chinese Dictionary