1. 小明编写了一个寻找奇妙整数的VB程序。此整数的平方与立方正好用了0~9的10个数且每个数只用一次，例如69的平方为4761，69的立方为：328509，4761和328509刚好用了0~9的10数，并且没有重复使用。现需从1至1000寻找这样的奇妙整数并在列表框List1中显示。实现上述功能的VB程序段如下：

Private Sub.Command1_Click()

Dim n As Integer, k As Integer, f As Boolean    ‘判断字符k是否重复出现

Dim s1 As String, s2 As String, i As Integer, j As Integer

For n= 1 To 1000

For i =0 To 9

a(i)= True

Next i

f = True

s1=CStr(n^2)

s2 =CStr(n^3)    ‘Cstr()函数的作用是将数字型变量改变成字符型变量

For j = 1 To Len(s1)

     ①   

If a(k)= True Then

a(k)=False

Else

f = False

Exit For

End If

Next j

If     ②      Then

j=0

Do While j<=9

If a(i)=True Then f=False: Exit Do

j=j+1

Loop

If f = True Then List1. AddItem Str(n)

End If

Next n

End Sub

Function Judge(s As String) As Boolean

Dim i As Integer, k As Integer

i=1: Judge True

Do While     ③   

k =Val(Mid(s, i, 1))

If a(k)=True Then

a(k)=False

Else

Judge = False

Exit Do

End If

i=i+1

Loop

End Function

请在程序划线处填入合适的代码。

① ② ③