发牢骚者

例句：

1. 1. He's always the first to speak up and express his frustrations.
   他总是第一个站出来表达他的挫败感。
2. 2. The manager was accused of being a frequent complainer.
   经理被指控经常抱怨。
3. 3. She often vents her frustrations by posting angry comments on social media.
   她经常通过在社交媒体上发表愤怒的评论来发泄她的不满。