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

betty is on duty today.she is c___ the blackborad with an eraser. is on duty today who is on duty who is on duty today what is on duty today? Who is on duty today?为什么用on duty _____lily______?A.Is,on duty B.Dose,on duty Who is on duty today ?是什么意思 谢谢 whose turn is it ( ) on duty today [what who whose]is on duty? on duty on duty The police are duty on the duty on road.这里为什么用are 而不是用is? whose turn is it-------（be） on duty today Today is my on duty for the day. is duty the on policeman怎么连词成句急 ____is on duty today?Li Lei is.怎么填? 若（X-4）×M=X的平方-X+N 则M=?N=?Betty is on duty today.She is c____ the blackboard with an eraser.On,why?You are b____ your white shoes with black shoe cream.以下是几条含有天气类单词的短语,你能猜出画线部分的意义吗?1