I did badly on that project and had to redo it.

did 是动词 do 的过去式，表示"做、完成"的动作。 badly 是副词，由形容词 bad（坏的、差的）加上后缀 -ly 构成，表示"不好地、糟糕地"。 did badly 这个短语表示"做得不好、表现不佳"。