问在类中更新的列表

EN

class A(object):
    aalist = []
    ai = 0
    def __init__(self):
    self.ablist = list()
    def add(self):
        self.aalist.append(["a","a"])
        self.ablist.append(["b","b"])
        self.ai = self.ai + 1
class B(A):
    def __init__(self):
        A.__init__(self)
        self.bblist = list()
    def badd(self):
        self.bblist.append(['c','c'])
for i in range(1,4):
    c = B()
    c.add()
    c.badd()
    print c.aalist,c.ablist,c.bblist,c.ai

[['a', 'a']] [['b', 'b']] [['c', 'c']] 1
[['a', 'a'], ['a', 'a']] [['b', 'b']] [['c', 'c']] 1
[['a', 'a'], ['a', 'a'], ['a', 'a']] [['b', 'b']] [['c', 'c']] 1