如果要在括号里填一个单词,应该是 has 时态与 he says 一致,但后面的 he has bought the house 10 years before 就有问题了.before 是 ago 的过去,即过去的过去,通常不可用于现在完成时.这句话有两种英文说法：
1 (加括号里的单词)：He says that he (has) bought the house for 10 years.或者,
2 (不加括号里的单词)：He says that he bought the house 10 years before.买房子在他说话之前,所以要用before.