用a,an或the填空,不填用"/"表示。①Who is{#blank#}1{#/blank#}girl behind{#blank#}2{#/blank#}tree?
②{#blank#}3{#/blank#} old man has two children,{#blank#}4{#/blank#} son and{#blank#}5{#/blank#}daughter.
③This is{#blank#}6{#/blank#}orange. {#blank#}7{#/blank#} orange is Lucy's.