－Our classroom every day.－So it is. It’s our duty to keep it clean and tidy.A. cleans B. i

问题补充：

－Our classroom every day.

－So it is. It’s our duty to keep it clean and tidy.

A. cleans B. is cleaning C. is cleaned

答案：

解析：我们每天打扫教室。——就该如此。保持教室的干净整洁是我们的义务。好语境可知上文描述的是经常性动作，故用一般现在时态。句子主语是动作对象，故用被动语态。选C。