题目

小明用VB编写了统计短文（不超过500字）中英语单词频次的程序。在文本框Text1中输入短文，单击“单词统计”按钮Count后，在列表框List1中按字典升序输出单词（不区分大小写）和出现频次，程序运行结果如图所示。 请回答下列问题： （1） 观察程序代码，该事件处理过程名为。 （2） 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 Count_Click()     Dim word(1 To 500) As String, num(1 To 500) As Integer     Dim s As String, c As String, tmp As String, t As Integer     Dim i As Integer, j As Integer, k As Integer, low As Integer, high As Integer     Dim m As Integer, n As Integer, b As Integer     For i = 1 To 500         num(i) = 0     Next i     s = Text1.Text : n = Len(s)     i = 1 : b = 1 : m = 0 : j = 0     Do While i <= n         c = Mid(s, i, 1)         If c >= "A" And c <= "Z" Or c >= "a" And c <= "z" Then             j = j + 1         Else             If j > 0 Then                 tmp =                  low = 1                 high = m                 Do While low <= high                     t = (low + high) \ 2                     If tmp = word(t) Then                         Exit Do                     If tmp < word(t) Then                         high = t - 1                     Else                         low = t + 1                 Loop                 If   Then                     For k = m To low Step -1                         word(k + 1) = word(k)                         num(k + 1) = num(k)                     Next k                                           num(low) = 1                     m = m + 1                 Else                     num(t) = num(t) + 1                 End If                 j = 0             End If             b = i + 1         End If         i = i + 1     Loop     List1.Clear     For i = 1 To m         List1.AddItem word(i) + ":" + Str(num(i)) + "次"     Next i End Sub Function Lowcase(t As String) As String     Dim c As String, s As String, i As Integer     s = ""     For i = 1 To Len(t)         c = Mid(t, i, 1)         If c >= "A" And c <= "Z" Then s = s + Chr(Asc(c) + 32) Else s = s + c     Next i       End Function 答案： 【1】Count_Click() 【1】Lowcase(Mid(s, b, j))【2】low > high【3】word(low) = tmp或 word(k+1)=tmp【4】Lowcase = s

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