moan

n. 呻吟声,悲叹声,抱怨声
v. 抱怨,呻吟
vi. 呻吟

What is he moaning about?

他在发什么牢骚？

He moaned about his misfortunes to anyone who would listen.

他向每一个愿意听的人抱怨他的不幸。