flutter|fluttered|fluttering

树叶在微风中轻轻颤动。

The leaves ___flutter gently in the breeze.

一阵风吹过，树叶飞舞。

A gust of wind blew, and the leaves ___fluttered.

旗帜在微风中轻轻飘动。

The flags are gently ___fluttering in the breeze.