Private Sub Command1Click()

Dim num(0 To 5) As Integer

Dim i As Integer, j As Integer

Dim t As Integer

num(0) = 4: num(1) = 7: num(2) = 2: num(3) = 0: num(4) = 3: num(5) = 9

i = 0: j = 1: t = 0

For i = 1 To 5 Step 1

  For j = i + 1 To 4 Step 1

  If num(i) > num(j) Then

  t = num(i)

  num(i) = num(j)

  num(j) = t

  End If

  Next j

Next i

For i = 1 To 5

List1.AddItem num(i)

Next i

End Sub

  For i=1 To 3

    For j=6 To i+1 Step-1

        If a(i)<a(j) Then

          T=a(i)：a(i)=a(i)：a(i)=t

        End If

    Next j

  Next i

数组元素a(1)到a(6)的值依次为“28，3，15，1，35，7”，执行该程序段，下列说法正确的是 （  ）

Private Sub Command1_Click()

Dim s As String, a As String, t As String

s = Text1.Text: t = ""

For i = 1 To Len(s)

    a = Mid(s, i, 1)

    If a >= "0" And a <= "9" Then

        t = t + a

    ElseIf a = "!" Then

        t = ""

    ElseIf t <> "" Then

        List1.AddItem t

    End If

Next i

End Sub

执行程序时，在文本框 Text1 中输入“12+34=46!789ok”（不包括双引号），单击按钮Command1后，在列表框List1中显示的结果是（  ）

a(1) = "20": a(2) = "18": a(3) = "06": a(4) = "o": a(5) = "k"

For i = 1 To 4

   For j = 2 To 6-i

        If a(j) > a(j-1) Then t = a(j): a(j) = a(j-1): a(j-1) = t

       Next j

       List1.Additem a(j-1)

Next i

执行该算法，输入n的值为13，下列说法正确的是(    )