a(1)=False

For i = 2 To 20

       a(i) = True

Next i

For i = 2 To 20

      If a(i) = True Then

        For j = 2 To 20 \ i

          a(i * j) = False

        Next j

      End If

Next i

t = 0

For i = 1 To 20

      If a(i) = True Then

        t = t + 1

      End If

Next i

经过该程序段运行后，变量t的值为（   ）

Dim min As Single ,  d2 As Double , abc As String

则变量min的类型是({#blank#}1{#/blank#}) ，变量d2的类型是({#blank#}2{#/blank#}) ，变量abc的类型是({#blank#}3{#/blank#})。

A.可变类型   B.单精度型   C.双精度型   D.字符串型

Dim a(l To 100) As String

Private Sub Commandl_Click()

  Dim c As Integer, t As String, ans As String

  s = Textl. Text

  k = Val(Text2. Text)

  ans =“”

  For i = 1 To Len(s) - k - 1

    c = c + 1

    a(c) = Mid(s, i, 1) + Mid(s, i + k + 1, 1)

    If check(c) Then

      ans = ans + a(c) + "，"

    Else

      c = c - 1

    End If

  Next i

  Text3. Text = ans

End Sub

Function check(k As Integer) As Boolean

  Dim i As Integer

  check = True

  For i = 1 To k - 1

    If a(i) = a(k) Then check = False: Exit For

  Next i

End Function

若该程序段执行后，在文本框Text1中输入的字符串长度不超过10，文本框Text2中输入的值在0到8范围内（输入输出都不包括双引号本身），下列说法不正确的是（  ）

实现以上功能的VB程序如下,在横处填入合适的代码。

Dim a(1 To 20) As Integer     ‘存储区间的左端点数值

Dim b(1 To 20) As Integer     ‘存储区间的右端点数值

Private Sub Form_Load()

‘将区间左端点存入数组a,区间右端点存入数组b,并在列表框List1显示,代码略

End Sub

Private Sub Command1_Click()

Dim i As Integer, j As Integer

Dim curL As Integer, curR As Integer

For i=1 To n-1

 For j=1 To n-i

  If{#blank#}1{#/blank#}Then

   t=a(j): a(j)=a(j+1): a(j+1)=t

   t=b(j): b(j)=b(j+1): b(j+1)=t

  End If

 Next j

Next i

curL=a(1): curR=b(1)

For i=2 To n

 If{#blank#}2{#/blank#}Then

  If curR < b(i) Then{#blank#}3{#/blank#}

 Else

  List2.AddItem“["+Str(curL)+Str(curR)+"]”

  curL=a(i): curR=b(i)

 End If

Next i

List2. AddItem “[”+Str(curL)+Str(curR)+“]”

End Sub

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