孩子们在派对上开心地唱歌。

The children happily ___sang at the party.

水快烧开时，茶壶发出鸣叫声。

The teapot ___sings as the water is about to boil.

那个小偷害怕同伙会向警方告发他。

The thief was afraid his partners would ___sing on him to the cops.