考虑如下的定义类时，类之间的多继承关系，要求：(1)根据类定义的关系画出继承关系图；(2)类D的mro属性值是多少? class A1: pass class A2: pass class A3: pass class B1(A1,A2): pass class B2(A2,A3): pass class B3(A3): pass class C1(B1): pass class C2(B1,B2): pass class C3(B2,B3): pass class D(C1,C2,C3): pass

继承关系图如下：

    A1    A2    A3
     |     |     |
     B1----B2----B3
      \   / \   /
       \ /   \ /
       C1    C3
        \   /
         \ /
         C2
          |
          D

类D的mro属性值为[D, C1, C2, B1, B2, B3, A1, A2, A3, object]。