mumbling
n. 含糊的话语，咕哝
v. 含糊地说，咕哝；（用无齿牙床）困难地咀嚼（mumble 的现在分词）
例句
I could hear him mumbling to himself.
我听到他在喃喃自语。
《牛津词典》
What are you mumbling to yourself?
你在嘀咕什么？
He closed his eyes, fell to mumbling, and presently was silent.
他闭上眼睛，喃喃自语起来，不一会儿就沉默了。
