程序运行时，在Text1中输入字符串，单击“开始统计”按钮，在List1中显示统计结果。函数IsLetter(x)功能，若x是字母，则返回值为字母x在字母序列“A”~“Z”中的序号，如字母“A”的序号为0，字母“D”的序号为3。若x不是字母，则返回值为-1。

Function IsLetter(x As String) As Integer

        If "A" <= x And x <= "Z" Then

            IsLetter = Asc(x) - Asc("A")

        ElseIf "a" <= x And x <= "z" Then

            IsLetter = Asc(x) - Asc("a")

        Else

                       ①        

        End If

    End Function

    Private Sub Command1_Click()

        Dim d(25) As Integer, m As Integer, n As Integer

        Dim s As String, c As String

        List1.Clear

        For m = 0 To 25                  '初始化数组d

            d(m) = 0

        Next m

        s = Text1.Text

        For m = 1 To Len(s)              '读取字符串中的字符进行判断

            c = Mid(s, m, 1)

            n = IsLetter(c)

            If n <> -1 Then    ②  

        Next m

        For m = 0 To 25                  '输出结果

            If    ③   Then

               List1.AddItem (Chr(m + Asc("a")) & ":" & d(m))

            End If

        Next m

   End Sub

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m=a(1)

For i=2  to  100

  If  a(i) > m  then  m=a(i)

Next i

该程序段执行后，变量m中存储的是(   )

Private Sub Command1_Click（）

  Dim s1 As String，s2 As String   

  Dim ch As String，ch2 As String   

  Dim max As Double   

  Dim n As Integer，page As Integer  

  Dim i As Integer，j As Integer

  s1=Text1．Text：s2=””

  n=Len(s1)

  i=1：max=0

  Do While i<=n

    ch=Mid(s1，i，1)

    If ch>=“0”And ch<=“9”Then

        j=i

        ch2=Mid(s1，i，1)

        Do While ch2>=“0”And ch2<=“9”

           j=j+1

           ch2=Mid(s1，j, 1)

        Loop

        s2=    ’(1)

        If   Then    ’(2)

            max=Val(s2)

            page=i*10+j-1

            Text2．Text=Str(page)

            Text3．Text=Str(max Mod l00)

        End If

        i=j

      End If

      i=i+1

    Loop

  End Sub

a = a * b

b = a / b

a = a / b

a = 1

For p=1 to 50

   If  p Mod 3 = 0  Then  a = a + 1

Next p

Dim a(1 To 100) As Integer, n As Integer

Function moving( start As Integer, finish As Integer, st As Integer)

'将元素 a(finish)插入到元素 a(start)和元素 a(start+st)之间

Dim i As Integer, k As Integer k = a(finish)

For i = finish - st To start Step -st a(i + st) = a(i)

Next i a(start) = k

End Function

Private Sub Command1_Click()

Dim head As Integer, end1 As Integer, i As Integer, ans As String

' 将待排序的数存储在数组 a 的 a(1)至 a(n)中，并输入元素个数 n，代码略

head = 1: end1 = n + 1

Do While head < end1

If    ①    Then

For i = 1 To head - 1

If a(i) > a(head) Then Exit For

Next i

Call moving(i, head, 1)

head =     ②    

Else

For i = end1 To n

If a(i) < a(head) Then Exit For

Next i

Call moving(    ③    )

End1 = end1 - 1

End If

Loop

For i = 1 To n

ans = ans + Str(a(i))

Next i

Text2.Text = ans End Sub 请回答下列问题：