即席演说

例句：

1. 1.He gave an impromptu speech on the topic of climate change.
   他在气候变化的主题上进行了一次即席演讲。
2. 2. The performer was so good that he could give an impromptu performance.
   这位表演者非常出色，能够即席表演。
3. 3.The audience was captivated by his impromptu rendition of a classic song.
   观众被他即席演绎的经典歌曲深深吸引。