                   

                 

                

                     

               

                        

                

                  

           

                    

         A   B           

    B          A    

     

                       

                  

                 

                   

  

                     

         A              

                  

             A     

  

                       

                  

       

                  

                       

    

    ⑴                    

    ⑵                     

                     

                   

                  

     

    ⑶                     

                  

 

                   

         

                        

                      

                  

                

                

                 

        

                       

                 

           