同意rouxinshi的解释
整个句子只是在说一个过去的事实,用过去时.
现在完成时一般都含有强调过去与现在的联系的意味,从句中看不出这点.
例如：
-Hi,Tim.Where's Sam?I didn't find him in the library.
-He's(=He has) gone to classroom.(言下之意是So you can't find him in the library)