betty is on duty today.she is c___ the blackborad with an eraser._数学解答

betty is on duty today.she is c___ the blackborad with an eraser.

人气：170 ℃　时间：2019-11-02 17:20:37

解答

cleaning擦黑板
如还有不懂的,还可以继续追问哦\(^o^)/~