zhè / shǒu / biàn / zòu / qǔ / yǐ / jiǎn / dān / de / zhǔ / tí / kāi / shǐ / hòu / lái / biàn / de / yuè / lái / yuè / fù / zá

这首变奏曲以简单的主题开始，后来变得越来越复杂。

This variation begins with a simple theme and gradually becomes more complex.