Dim m2 As String

Private Sub Command1Click()

Dim flag(1 To 26) As Boolean

Dim num As Integer,t As Integer

Randomize

num = 1

Text3.Text = " "

For i = 1 To 26

    flag(i) = False

Next i

Do While num <= 26

    x = Int(Rnd * 26) + 97

          ①      

    If  flag(t) = False Then

    m2 = m2 + Chr(x)

    num = num + 1

      ②       

    End If

Loop

Text3.Text = m2

End Sub

Private Sub Command2Click()

Dim s As String， m As String， result As String

Dim k As String， c As Integer

s = Text1.Text

m = "abcdefghijklmnopqrstuvwxyz"

For i = 1 To Len(s)

    k = Mid(s, i, 1)

    If  k >= "A" And k <= "Z"  Then

    k = Chr(Asc(k) + 32)

    End If

    c = 1: continue = True

    Do While       ③       

    If k = Mid(m, c, 1) Then

    continue = False

    End If

    c = c + 1

    Loop

   ④     

Next i

Text2.Text = result

End Sub

程序①处的代码是{#blank#}1{#/blank#}

程序②处的代码是{#blank#}2{#/blank#}

程序③处的代码是{#blank#}3{#/blank#}

程序④处的代码是{#blank#}4{#/blank#}

实现上述功能的VB程序如下，但加框处代码有错，请改正。

Const n = 10    ‘数组元素的总数

Dim a(1 To n) As Integer

Private Sub Form_Load()

‘该过程对数组a进行赋值,并在列表框List1中显示，代码略

End Sub

Private Sub Command1_Click()

Dim i As Integer, j As Integer,flag(1 To n) As Boolean

‘flag(i)记录第i个元素是否重复出现

For i = 1 To n      ‘flag(i)=true开始假设都只出现1次

 flag(i) = True

Next i

For i = 1 To n

 If flag(i) Then

  For j = i + 1 To n

    If Then flag(i) = False: flag(j) = False    ‘①

  Next j

 End If

Next i

For i = 1 To n

  If Then List2.AddItem Str(a(i))    ‘②

Next i

End Sub

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

Dim n As Integer, i As Integer, left As Integer, right As Integer, m As Integer

Dim a(1 To 10) As String, t As String, key As String n = 6

a(1) = "35": a(2) = "20": a(3) = "18": a(4) = "8": a(5) = "274": a(6) = "47" For i = 1 To n - 1

For j = n To i + 1 Step -1

If a(i) < a(j) Then

t = a(i): a(i) = a(j): a(j) = t

End If

Next j

Next i

key = Text1.Text

left = 1: right = n

Do While left <= right

m = (left + right) \ 2

If a(m) = key Then Exit Do

If a(m) < key Then right = m - 1 Else left = m + 1

Loop

若在文本框 Text1 中输入“212”，则程序运行结束后，m 的值为（  ）

Key=Val(Text1.Text)\10

Text2.Text=“”

i=1: j=9: f=False

Do While i<=j And Not f

    m=(i+j)\2

    if a(m) Mod 10=Key Then

        search=m

        f=True

    Elseif a(m) Mod 10>Key Then

        i=m+1

    Else

        j=m-1

    End if

    Text2.Text=Text2.Text+Str(m)

Loop

则在执行该程序后，Text2中显示的内容是（    ）