刚刚学习vb，问一些简单的问题...谢谢各位了！！vb中怎样弄A到Z的随机数，随机出现一个，而且不重复？

Private Sub Command1_Click()
Static num(65 To 90), c As Integer
If c = 26 Then Exit Sub
c = c + 1
Dim s, i
Randomize
begin:
s = Int(Rnd() * (90 - 65 + 1)) + 65
If num(s) <> 1 Then
i = Chr(s)
num(s) = 1
Else
GoTo begin:
End If
Print i;
End Sub