喃喃低语声

例句：

1. 1.She muttered under her breath as she walked away.
   她小声嘀咕着走开了。
2. 2.He murmured a secret to his friend in the dark.
   他在黑暗中对朋友低声说了一个秘密。
3. 3. The old man muttered about the weather as he sat by the window.
   老人坐在窗边，低声谈论着天气。