选择以下的句子补全对话
A.Thankyouverymuch.
B.No,itisn't.
C.Whereisit?
D.Isitunderthetable?
E.Yes,itis.
1.Ican'tfindmybackpack.
2.Don'tworry.________
3.___________
4.Isitonthedresser?
5.No,itisn't.
6.Ah,Ifindyourbackpack.
7._________
8.Itisonyourback,butyoudon'tknow.
9.Ah,_______________