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)