The teacher-(not teach)us a chinese song,he-(teach)us an eng

didn't teach,taught
two days ago 表示：两天前,是过去时间,所以用一般过去时态.
再问： hasn't taught,taught和didn't teach, taught一样吗？它们有什么区别？
再答： hasn't taught 是用的现在完成时，didn't teach用的是一般过去时，这两者时态不一致。