按要求转换句型（共计10分,每空一词，每空1分）
Her book is on the desk.(根据划线部分提问)
_______ _______ her book?
Those are erasers.(改为单数句)
That _______ ______ eraser.
His sister likes red pens.(改为一般疑问句)
______ his sister ________ red pens?
My favorite subject is geography.(根据划线部分提问)
_______ ________  favorite subject?
How much are the trousers?(改为同义句)
________ the _______ of the trousers?