下面的程序功能是将一个由字母与数字相混的字符串中选出字母串,并把该字母串在窗体上打印出来,请完善程序。 Option Explicit Private Sub Command1_Click() Dim S As String , k As Integer Dim r As String , i As Integer , t As String S= " aa11bb22cc33 " For i = 1 To (1 ) t= ( 2 ) If t>= " a " And t<= " z " Or t>= " A " And t<= " Z " Then r = r & t End If Next i Print r End Sub