In the concert,there are three piano solos.在音乐会上，有三首钢琴独奏曲。

用作定语
▲～+n.
I made my first solo flight.我第一次做了单人飞行。
Composers have written vast amounts of music for solo piano.作曲家们已谱写了大量的钢琴独奏曲。

The flying-instructor told her she was to fly solo the next day.飞行教练告诉她第二天单飞。
Mr. Burke carried on with the climb solo.伯克先生孤身一人继续登山。