程序代码如下：

Private Sub Command1_Click()

  Dim i As Integer

  List1.Clear  '清除列表框内容

End Sub

Private Function f(x As Integer) As Boolean  '判断是否为素数，若是返回true,若不是则返回false

………

End Function

图1

徐明设计了一个VB程序用于寻找这个以211开头、可被2012整除的6位数。其算法流程图如图2所示，程序界面如图3所示，程序的代码编辑窗口如图4所示。

图2

为实现上述功能程序如下，但加框处的代码有误，请改正。

Private Sub Command1_Click()

    Dim n As Integer

    Dim i As Integer, c As Integer

    n = Val(Text1.Text)

    List1.Clear

    c = 0

    If n Mod 2 = 0 Then

        For        ①

            If    Then            ②

                List1.AddItem n & "=" & i & "+" & n - i

                c = c + 1

            End If

        Next i

        Label2.Caption = "共有" & c & "种组合"

    Else

        Label2.Caption = "请输入一个大于 2 的偶数"

    End If

End Sub

Function is Prime(x As Integer) As Boolean

    Dim i As Integer

    Is Prime = True

    For i = 2 To Int(Sqr(x))

        If x Mod i = 0 Then

            Is Prime = False

            Exit For

        End If

    Next i

End Function

①{#blank#}1{#/blank#} ②{#blank#}2{#/blank#}