根据对话内容,在每个空白处填入一个适当的词,使对话完整,合乎情景
A:（ ）,Jim!There is a big bag uhder the tree.
B:What is in （
A:I（ ）know.I guess（ ）are some books.
B:( ).I think there（ ）a football.
A:( )go and open it.
B:Ah,there are some books and a football.
A：Oh,there's a （ ）on the bag-David Smith.
B:It’s （ ）.Let's go and give him （ ）bag.