1. She hummed a catchy ditty as she walked down the street.
她走在街上哼着一首动听的小曲。

2. The children sang a playful ditty during the school assembly.
孩子们在学校集会上唱了一首欢快的小调。

3. The commercial used a catchy ditty to promote their product.
这则广告使用了一首动听的小歌来推销他们的产品。