来自何楚的问题
【Thenoticeonthewallismeantto______theunwantedvisitors，especiallyduringworkinghours．（）A.keepupB.keepoffC.keepfromD.keepback】
The notice on the wall is meant to______the unwanted visitors，especially duringworking hours．（）
A.keep up
B.keep off
C.keep from
D.keep back
