句型转换。按要求改写下列句子，每空一词。
1．There is a book on the desk. (改为一般疑问句)
            a book on the desk?
2．There are some cakes in the fridge. (改为否定句)
There       cakes in the fridge.
3．There is a girl under the tree. (就划线部分提问)
______ ______ _______ ________ there under the tree?
4．many, books, the, how, on, desk, there, are(?)(连词成句)