小明编写统计字符串中出现最多的字母和数字的程序。程序运行如下:在文本框Text1中输入一个仅包含字母和数字的字符串。单击按钮Command1后，在标签Label1上显示出现最多的数字字符，在标签Label2上显示出现最多的字母字符(字母不区分大小写，例如字母G和g统计在一起)。程序运行界面如图所示。
实现上述功能的VB程序如下，请在划线处填入合适的代码。
Private Sub Command1_Click()
Dim a(1 To 10) As Integer ‘存储0~9每个数字出现的次数
Dim b(1 To 26) As Integer ‘存储a~z每个字母出现的次数
Dim zf As String, x As String, p As Integer
Dim maxa As Integer, maxb As Integer
{#blank#}1{#/blank#}
For i = 1 To Len(zf)
x = Mid(zf, i, 1)
If pd(x) = 1 Then
p = Asc(x) - Asc(“0”) + 1
a(p) = a(p) + 1
{#blank#}2{#/blank#}
p = Asc(x) - Asc(“A”) + 1
b(p) = b(p) + 1
Else
p = Asc(x) - Asc(“a”) + 1
b(p) = b(p) + 1
End If
Next i
k = a(1):maxa = 1
For i = 2 To 10
If a(i) > k Then k = a(i):maxa = i
Next i
k = b(1) :maxb = 1
For i = 2 To 26
If{#blank#}3{#/blank#}Then k = b(i) :maxb = i
Next i
Label1.Caption =“出现最多的数字是” + Chr(maxa+ Asc(“0”)-1)
Label2.Caption = “出现最多的字母是” + Chr(maxb + Asc(“A”)-1)
End Sub
Function pd(ch As String) As Integer ’函数用于判断每个字符类型
If ch >= “0” And ch <= “9” Then pd = 2
If ch >= “A” And ch <= “Z” Then pd = 2
If ch >= “a” And ch <= “z” Then pd = 3
End Function
Then