Tom said that he -----(can finish) the work in two days. 快 急

Tom said that he could finish (can finish) the work in two days
原来从句中时态应用can finish,因为主句是过去式,所以从句时态要往前推一格,所以用过去式
再问： 谢谢，你是英语老师么？那Our English teacher said i __________（不用功）。怎么做？
再答： 不是 Our English teacher said I didn't work hard
再问： 为什么是didn't不是don't
再答： 因为主句时态是一般过去时，从句时态要往前推一格的