她一边做家务一边哼着欢快的小调。

She was ___warbling a cheerful tune while doing housework.

她在淋浴时用颤音哼唱着最喜欢的歌。

She was ___warbling her favorite song with a quivering voice in the shower.

音响系统播放的音乐在高音部分有些失真，发出吱吱的颤音。

The music from the sound system had a slight distortion, ___warbling on the high notes.