1.moan的基本意思是“呻吟”“悲叹”,指发出一种低沉的、拉长的、含糊不清的声音,以表明身心遭受痛苦,也可引申指“痛苦”“抱怨”等。
2.moan既可用作不及物动词,也可用作及物动词。用作及物动词时,可接名词、代词或以that引导的从句作宾语; 用作不及物动词时,常与about, for, over等词连用,表示“为…而抱怨〔悲叹〕”。

moan about(v.+prep.)
〈非正〉为…抱怨 complain about (sth or doing sth), sometimes without cause
〔说明〕 moan about常用于进行体。
▲moan about sth/v-ing
You're always moaning about money.你总是为钱而抱怨。
What are you moaning about this time?这次你有什么可抱怨的?
Cage is always moaning about not being treated equally.凯奇总是抱怨别人对她不公。

moan out(v.+adv.)
发出呻吟声 groan a sound out
▲moan sth ⇔ out
Facer moaned out a sound and then closed his eyes.费塞呻吟了一声,然后就闭上了眼睛。

moan over(v.+prep.)
就…而悲叹〔哀悼〕 say with moans over sth
▲moan over sth
They were moaning over the death of their father.他们正在哀悼他们的父亲。

用作不及物动词
▲S+～(+A)
The sick woman moaned.那位生病的女人在呻吟。
The wounded man moaned ceaselessly.那个伤员呻吟不止。
The old woman moaned in her sleep.那老妇人在睡梦中呻吟着。
The wind moaned through the trees.风呜咽着穿过树林。
Stop moaning; you really have nothing to complain about.别悲叹了,你真的没什么好抱怨的。
用作及物动词
▲S+～+n./pron.
The prisoner moaned a prayer for help.囚犯呻吟着祈求帮助。
▲S+～+that-clause
She wept and moaned that her husband had abandoned her.她哭泣着悲叹丈夫遗弃了她。
She's always moaning that she has too much work to do.她总是抱怨她有太多的事要做。

moan, groan
这组词都可表示“呻吟,抱怨”,有时可互换。它们的区别是:groan可表示反对的“哼声”或对非议、烦恼等的“抱怨”; moan除了作“呻吟,呜咽”解外,还可指因悲哀而发出“悲叹”“抱怨”,即“哀怨”。

［同义词］ n.  groan, grumble, lament

From time to time there was a moan of pain from the sick man.病人不时发出一声声痛苦的呻吟。
They get fed up with her moans.她的抱怨令他们感到厌烦。