【正确答案】正确答案：【操作步骤】 步骤1：打开本题工程文件。 步骤2：分析并编写程序代码。 程序提供代码 Dim an As Integer Dim bn As Integer Dim cn As Integer Dim dn As Integer Private Sub Command1_Click() Open App.Path & "/in5.txt" For Input As #1 Do While Not EOF(1) Input #1, a$ s = s & a$ Loop Close 1 Text1.Text = s End Sub Private Sub Command2_Click() '需要考生编写的内容 End Sub Private Sub Command3_Click() Open App.Path & "/out5.txt" For Output As #1 Print #1, an, bn, cn, dn Close 1 End Sub 程序结束 参考答案 n = Len(Text1) For k = 1 To n ch = Mid(Text1, k, 1) If UCase(ch) = "A" Then an = an + 1 End If If UCase(ch) = "B" Then bn = bn + 1 End If If UCase(ch) = "C" Then cn = cn + 1 End If If UCase(ch) = "D" Then dn = dn + 1 End If Next k Text1 = an & " " & bn & " " & cn & " " & dn 步骤3：调试并运行程序，关闭程序后按题目要求存盘。