他在聚会上用小提琴演奏了一首欢快的曲子。

He ___fiddles a cheerful tune on his violin at the party.

他不停地摆弄手机屏幕，但什么都没做。

He kept ___fiddling with his phone screen but didn't actually do anything.

他因在报税时做手脚而被罚款。

He got fined for ___fiddling with the tax returns.