l1=[1,2,3,4,5,6，7,8,9]l1.append(['c','d',['adfas']])print(l1）输出：
l1=[1,2,3,4,5,6，7,8,9]l1.append(['c','d',['adfas']])print(l1）输出：
1
l1=[1,2,3,4,5,6，7,8,9]l1.append(['c','d',['adfas']])print(l1）输出：