婴儿开始咿咿呀呀地发声了。

The baby is ___vocalizing by making cute babbling sounds.

学生们在会议上大声表达他们的担忧。

The students were ___vocalizing their concerns loudly during the meeting.

练习发音时，清晰地发出每个元音很重要。

When practicing pronunciation, it's important to clearly ___vocalize each vowel sound.