4 sentences

1. 你又在叹气了。

   nǐ yòu zài tàn​qì le.

   You're sighing again.

   Source: OpenSubtitles

2. 你干嘛叹气？

   nǐ gàn​má tàn​qì?

   Why are you sighing?

   Source: OpenSubtitles

3. 遇到困难不要总是叹气，要多想办法。

   yù​dào kùn​nan bù​yào zǒng​shì tàn​qì, yào duō xiǎng bàn​fǎ.

   Don't just sigh when you encounter difficulties; think of more ways to solve them.

   Source: Dong Chinese Dictionary

4. 他在房间里不安地走动，时而低头，时而叹气。

   tā zài fáng​jiān lǐ bù'ān de zǒu​dòng, shí'ér dī​tóu, shí'ér tàn​qì.

   He paced restlessly around the room, now bowing his head, now sighing.

   Source: Dong Chinese Dictionary