这句改错怎么改?.I spent five days on this work,it was a difficult work.

work改为job，因为work是不可数名词，前不能用a

I spent five days on this work,it was a difficult work. 这是两个句子不能用逗号连接，可以考虑改为定语从句——I spent five days on this work which was difficult.

去掉a