统计不同单词个数,在Text1中输入一行单词,点击“统计”按钮后在Text2中输出不同单词的个数。单词字母有大小写,同一单词的大小字母视为相同,句子以符号结尾, 程序运行界面如图所示。

(1)观察以下代码,该代码中 Command1_Click()是
【小题1】(选:
(2)实现上述功能的VB程序如下,请在划线处填入合适代码。
Private Sub Command1_Click()
Dim a(1 To 100) As String ,s As String, ch As String, word As String
Dim i As Integer, j As Integer, k As Integer, numb As Integer
s = Text1.Text : k = 0 : word = ""
For i = 1 To Len(s)
ch = Mid(s, i, 1)
If ch >= "a" And ch <= "z" Or ch >= "A" And ch <= "Z" Then
If ch >= "A" And ch <= "Z" Then
①【小题2】 word = word + ch
Else
flag = False
For j = 1 To k
If a(j) = word Then flag = True
Next j
If Not flag And word <> "" Then
②【小题3】 a(k) = word
numb = numb + 1
End If
③【小题4】 End If
Next i
Text2.Text = str(numb)
End Sub