实现上述功能的VB程序如下，但加框处代码有错，请改正。

Private Sub Command1_Click()

  Dim s As String，i As Integer，s1 As String，sum As Integer，t As Integer

  Dim jy As Integer

  s＝Text1.Text

  t＝0：sum＝0

  For i＝1 To Len(s)

    s1＝Mid(s，i，1)

    If s1>＝“0” And s1<＝“9” Then

           ′①

        If t<10 Then

            sum＝sum＋Val(s1)*(11－t)

        ElseIf t＝10 Then

              ′②

        End If

    End If

  Next i

  sum＝11－sum Mod 11

  If  Then′③

    Text2.Text＝“该校验码中数字不是10位数！”

  Else

    If jy＝“X” and sum＝10 Then

      Text2.Text＝“校验通过”

    ElseIf val(jy)＝sum then

      Text2.Text＝“校验通过”

    Else

      Text2.Text＝“校验不通过”

    End If

  End If

End Sub

划线处代码为①{#blank#}1{#/blank#}

②{#blank#}2{#/blank#}

③{#blank#}3{#/blank#}

现编写一个VB程序，实现如下功能：在文本框Text1中产生条形码数字序列，单击“校验”按钮Command1，在标签Label1中输出对应的校验信息，界面如图所示。实现上述功能的VB程序如下，但加框处代码有错，请改正

Private Sub Command1_Click()

     Dim s As String, x As Integer

     Dim n As Integer , js As Integer, os As Integer, m As Integer

     Js=0: os=0

     s = Text1.Text

         {#blank#}1{#/blank#}

If n <> 13 Then

    Label1.Caption = "条形码位数错误!"

Else

    For i = 1 To 12

    {#blank#}2{#/blank#}  

      If x Mod 2 <> 0 Then

        js = js + x

      Else

        os = os + x

      End If

    Next i

    m = os * 3 + js

       {#blank#}3{#/blank#}

    If m=Val(Mid(s,n,1)) Then

      Label1.Caption = "校验码正确!"

    Else

       Label1.Caption = "校验码错误!"

    End If

End If

End Sub

x =    ①  

t = 0: s = ""

Do While x <> 0

    t =    ②  

    x = x \ 10

Loop

If    ③    Then Then Then s = "是9的倍数" Else s = "不是9的倍数"

count=0

For i=1 To 20

    a(i) =Int(Rnd*100) + 1

Next i

For i= 1 To 20

    ①

Next i

For i= 1 To 100

    If b(i) <> 0 Then count =count+1

Next i

Label 1.caption=“不重复数字个数”+Str(count)

为实现上述功能，则程序①处应填入的语句为（  ）

Dim a(1 To 10) As Integer，b(1 To 10) As Integer

k = 0

For i = 10 To 1 Step -1

Do While b(i) <> 0 k = k + 1

a(k) = i: b(i) = b(i) - 1

Loop

Next i

若 a(1)～a(10)的值分别为 7，9，8，1，9，4，4，2，1，1，则运行以上程序后，下列说法正确的是（  ）