n. a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech
n. 喃喃低语
vi. 喃喃自语, 作低沉声
vt. 出怨言, 抱怨地说
1. She tends to mutter when she is upset.
她在不高兴的时候常常低声嘀咕。
2. I could hear him mutter something under his breath.
我能听到他低声嘟囔着什么。
3. Don't mutter your answers; speak clearly so everyone can hear.
不要低声说出你的答案；要清楚地说，这样每个人都能听到。