你好，你可以说 “昨天早上北京下雪了吗？” Because the character "了" is a particle that indicates completion or past tense. It is often used to emphasize that a past event has finished or been completed. In this question, "了" emphasizes that the event of "yesterday's snow" has already happened and is asking if it has ended or completed.
下雪
比如 ( for example), 昨天早上在北京下雪吗?
谢谢老师。
你好，你可以说 “昨天早上北京下雪了吗？” Because the character "了" is a particle that indicates completion or past tense. It is often used to emphasize that a past event has finished or been completed. In this question, "了" emphasizes that the event of "yesterday's snow" has already happened and is asking if it has ended or completed.