即席即兴

例句：

1. 1. The band played an impromptu concert in the park last night.
   昨晚乐队在公园里进行了一次即兴音乐会。
2. 2. He was asked to give an impromptu speech at the meeting.
   他被要求在会议上进行一次即兴演讲。
3. 3.She decided to go for a walk in the park after hearing the impromptu announcement.
   在听到那个即兴宣布后，她决定去公园散步。