根据要求变换句型。
（1）The students are cleaning the classroom.（变一般问句作肯定回答）
                                                           
（2）The children have lunch at home。（改否定句）
                                                          
（3）The old man is sitting on the chair.（划线提问）
                                                           
（4）There are some potatoes on the table.（改单句）
                                                            
（5）Is this your pencil? （变陈述句）