编写下列代码，观察结果。
- list_2d = [ [0 for i in range(5)] for i in range(5)]
- list_2d[0].append(3)
- list_2d[0].append(5)
- list_2d[2].append(7)
- print(list_2d)
结果：
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- list_2d = [ [0 for i in range(5)] for i in range(5)]
- list_2d[0].append(3)
- list_2d[0].append(5)
- list_2d[2].append(7)
- print(list_2d)
