下面代码的执行结果是 ls = ["2020", "20.20", "Python"] ls.append(2020) ls.append([2020, "2020"]) print(ls) A. ['2020', '20.20', 'Python', 2020] B. ['2020', '20.20', 'Python', 2020, ['2020']] C. ['2020', '20.20', 'Python', 2020, [2020, '2020']] D. ['2020', '20.20', 'Python', 2020, 2020, '2020']