从方框中选择恰当的词并用适当形式填空，完成短文。

    Hey!  I'm Lucy. .Today is Sunday.  I don't go to school. .I am shopping ____  West Mall with my parents.  I see some good sweaters at the Mall. .And they are on ____.  The red sweater is only 40 yuan.  The yellow sweater is only 20 yuan.  My mother is ____ to the shop assistant. .Oh,  dear!  The shop assistant is my mother’s good friend.  She is Mrs Jones.  Her daughter, ,Linda is ____her mother sell sweaters. .Where is my father?  He is in front of the mall.  He is talking with a policeman and ____ for us. .Who is the policeman?  Sorry,  I don't know.