Frédéric Chopin’s Fantaisie-Impromptu in C-sharp minor, Op. posth. 66, is a solo piano composition. The Fantaisie-Impromptu was written in 1834, as were the Four Mazurkas (Op. 17), and the Grande valse brillante in E-flat major (Op. 18), but, unlike these other works, Chopin never published the Fantaisie-Impromptu. Fantaisie-Impromptu draws many of its harmonic and tonal elements from Beethoven’s Moonlight Sonata, which is also in C-sharp minor, in particular, the third movement.
肖邦的升c小调幻想即兴曲，是一首钢琴独奏曲。 写于1834年，Four Mazurka（Op.17）和降E大调的Grande valse brillante（Op.18），但与其他作品不同，肖邦从未发表过幻想即兴曲。 该曲从贝多芬的月光奏鸣曲中汲取了许多谐音和音调元素，这也是升C小调，特别是第三乐章。