She mumbled an apology and left.

她嘟嘟囔囔地道了歉就走了。

Teddy mumbled indistinctly.

泰迪含混不清地咕哝着。

He mumbled a few words.

他咕哝了几句。

Her grandmother mumbled in her sleep.

她祖母睡觉时咕哝了。

'Sorry,' she mumbled.

她含含糊糊地说：“对不起。”