3 sentences

1. 我真是松了一口气。

   wǒ zhēn shì sōng le yī​kǒu qì.

   I was so relieved.

   Source: OpenSubtitles

2. 他喝了一口水。

   tā hē le yī​kǒu shuǐ.

   He took a sip of water.

   Source: Dong Chinese Dictionary

3. 他一口拒绝了我的请求。

   tā yī​kǒu jù​jué le wǒ de qǐng​qiú.

   He flatly refused my request.

   Source: Dong Chinese Dictionary