程序代码如下：

Private Sub Command1_Click()

  Dim n As Integer, i As Integer

  List1.Clear

  n = Val(Text1.Text)

  If n Mod 2 = 0 Then

    For i = 2 To Int(n / 2)

      If isodd(i) = (isodd(n - i)) Then

        List1.AddItem Str(n) + " =" + Str(i) + " +" + Str(n - i)

      End If

    Next i

  Else

    Text1.Text = Str(n) + "不是偶数！"

  End If

End Sub

Private Function isodd(n As Integer) as boolean

   Dim f As integer

   f = 0

   For i = 2 To Sqr(n)

     If n Mod i = 0 Then f = 1: Exit For

   Next i

   isodd =  f

End Function

Dim a(1 To 100) As Single '依次存储100个学生成绩

Const n = 100

Private Sub Form_Load()

'本过程从数据库中读取1到100号学生成绩，并存储在数组a中

'代码略

End Sub

Private Sub Command1_Click()

Dim i As Integer, max As single

max =    ①      

For i = 2 To n

   if              ②                       

Next i

Text1.Text = "成绩最高分是：" + Str(max)

End Sub

上述流程图中虚线框部分的内容可为（   ）

n = 6

d(1) = 23: d(2) = 31: d(3) = 19: d(4) = 33: d(5) =58: d(6) = 28

k = Abs(d(2) - d(1))

For i = 3 To n

 If Abs(d(i) - d(i - 1)) > k Then k = Abs(d(i) - d(i - 1))

Next i

Text1.Text = Str(k)

上述程序段执行后，文本框Text1显示的内容是（  ）