在英语里几月几号用介词on,那为什么My birthday is May 1st.不用呢

My birthday is May 1st.
这里May1st 是做整句话的表语,不是说是在哪一天,而是说是几月几号.
老师祝你学习进步!
望采纳,多谢!^_^
再问： What's the date?It's on July 9th.那为什么用ON
再答： 不加。 What's the date? It's July 9th. I was born on July 9th.就不一样了。