猫咪高兴时经常会发出咕噜咕噜的声音。

The cat often ___vocalizes with purring sounds when happy.

当老师提问时，他总是积极表达自己的想法。

He always ___vocalizes his thoughts actively when the teacher asks questions.

这位歌手在练习时总是先哼唱几个音符来开嗓。

The singer always ___vocalizes a few notes to warm up before practicing.