2 sentences

1. 我这不是发牢骚。

   wǒ zhèi bù shì fā láo​sāo.

   I'm not complaining.

   Source: OpenSubtitles

2. 他满腹牢骚，总觉得自己受到了不公平的对待。

   tā mǎn​fù láo​sāo, zǒng jué​de zì​jǐ shòu​dào le bù gōng​píng de duì​dài.

   He is full of complaints and always feels he is being treated unfairly.

   Source: Dong Chinese Dictionary