咖啡机正冒着热气，发出轻轻的咕嘟声。

The coffee machine was ___burbling quietly as it brewed.

孩子们兴奋地叽叽喳喳说个不停，没人能听懂他们在说什么。

The kids were ___burbling excitedly, but no one could understand what they were saying.