    


                  
                   /
           С--ɽ
                 / 
    ĵ--ֱ 
                |                                       ʷ     
    Ϣ    |              Ժ    Ժ  |            ŮϢ
        |       |                   \           /        |              |
      С      |       ҩ       ƫ    ƫ              С
        |       |         |            \      /          |              |
       Ժ  С·  䳡    ǰͥ  䳡С·Ժ
        |                 |               |              |              |
       խ·                       |            С           ܹܷ(task)
        |                        |        |              |
       С                    ɽ·(wd)㳡         ֱ 
                                    \                    |
                                     \                  ̨
                                       һ          
                                           |(sd)
                                       һ
                                           |(sd)      
                           壨wd һ
                          /
                        վ
                          |sd
                         ɽ
                          |sd
                         ɽ            ̨
                            \   eu     eu  |
                            С塪ɽ· ֹ
                                           | sd
                                          ɽ·
                                           | su
                                         
