用方框中所给单词的适当形式填空,使对话通顺、正确。每词仅用一次(每空一词)。Helen: Are these your {#blank#}1{#/blank#} ?
Eric: No, they aren't. They're hers.
Helen: Is that {#blank#}2{#/blank#} schoolbag
Eric: No, it isn't. It's {#blank#}3{#/blank#} .
Helen: Is this your pencil?
Eric: Yes, it is. It's {#blank#}4{#/blank#} .
Helen: Excuse me, Grace. Are {#blank#}5{#/blank#} your books?
Grace: Yes, thank you.
Helen: You're welcome.