Private Sub Command1_Click()

Dim getStr As String

Dim a As String

Dim i As Integer，s As Integer

Dim q As Integer，l As Integer

s=0：q=0：l=0

getStr=Text1.Text

Text2.Text = Str（s）

Text3.Text = Str（q）

Text4.Text = Str（l）

End Sub

  k = 0                 '用来计数

  Max = 600             '指定范围600以内

  n = 9                                  

  Do While n <= Max

  Loop

  Label1.Caption = Str(Max) & "范围内满足问题的数有" & Str(k) & "个"

End Sub

方框中的代码由以下五部分组成：

① n=n+7

② k = k + 1

③ List1.AddItem Str(n)

④ End If

⑤ If n Mod 3 = 2 And n Mod 5 = 3 Then

代码顺序正确的选项是（  ）

实现上述功能的VB代码如下：

Private Sub Command1_Click() Dim a(0 To 4) As String Dim b(0 To 4) As Integer

Dim s As String, r As String

Dim i As Integer, j As Integer, k As Integer, c As Integer, n As Integer

List1.Clear

s = Text1.Text :   n = Len(s)

If         Then    '选填 Label1.Caption = "数据输入有误！"

Exit Sub   '退出 End If

For i = 0 To n - 1

a(i) = Mid(s, i + 1, 1) b(i) = 0

Next i c = 0

For i = 1 To n ^ n r = ""

For j = 0 To n - 1

Next j

c = c + 1 List1.AddItem r k = 0

b(k) = b(k) + 1

Do While b(k) = n And k < 4 b(k) = 0

b(k) = b(k) + 1 Loop

Next i

Label1.Caption = "构造字符串的方法共计" + Str(c) + "种。" End Sub

Function test(s As String) As Boolean ‘用于判别是否存在重复的字符，代码略

‘若无重复，则返回True，否则返回False

End Function

请回答下列问题：

按上述要求，编写VB程序，功能如下：在文本框Text1中输入n的值，点击“开始枚举”按钮Command1，在列表框List1中输出所有方案，在列表框List2中输出比例合适方案。

实现上述功能的VB程序如下，回答下列问题：