先通读下面的短文，掌握其大意，然后从A、B、C、D四个选项中选择可以填入空白处的最佳答案。
Hello，everyone!My name is Tony．Welcome to our school lost and found1．You can always2 some books or other things somewhere in me school because of the some careless(粗心的)students．Some students3 them and send them here．
Look!There is a nice pen.There's also a black bag4some books in it.Oh,here is Kate's 5on the bag.I think it's6．Look at the pencil case(铅笔盒)．There is a pen and two erasers in it．Under the table there are two7．Some boys like 8basketball after class．The basketballs are theirs,I think．Look at the cute toy dog．I don't know9 it is．
So everyone，be10your things．
是
，则条件①可为