Are your pencils in the desk?【肯定回答】

题目

Are your pencils in the desk?【肯定回答】
NO,___ ___.
Those are books.【改为单数句子】
___ ___ a book.
His book is in the backpack.（对in the backpack提问）
___ ___ his book?
They are his sisters.(否定句）
They ___ ___ his sisters.
Is Tom your brother?(肯定回答）
Yes,___ ___

答案

they aren't
That is
Where is
are not
he is