句子说全了啊The boy finishing his work, his mother allowed him to play a short while你们学过非谓语吗？这里finish做非谓语，allow做谓语动词。简单句中只有一个动词充当谓语，其余用非谓语形式：to do, doing, done。当然这里还可以这样改，When the boy finished his work, his mother allowed him to play a short while。不明白接着问