Question

－This yard is so clean today and everything looks fine. －I didn't notice that．It's clear someone________ it． [　　] A． cleans B． cleaned C． has cleaned

Answer 1

答案：C
解析：

句子意思是院子已经被打扫干净，这个动作已经完成，对现在造成的后果是现在很干净了，所以要用现在完成时。