a1=(1,2,3) a2={a1:3} a2 {(1, 2, 3): 3} a3=(1,[2,3]) a4={a3:1} Traceback (most recent call last): File "<pyshell#39>", line 1, in <module> a4={a3:1} TypeError: unhashable type: 'list' a4={a1:a3} a4 {(1, 2, 3): (1, [2, 3])}

key值本事必须为不可变对象，所以不能为list而set可以，value本身可变，所以可以为set或list