a) Uso del ciclo for Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click For contador = 1 To 5 ListBox1.Items.Add(contador) Next End Sub End Class b) Captura el siguiente programa para ingresar un usuario y contraseña: Public Class Form1 Public Usuario As String Public contraseña As String Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load End Sub Private Sub Txt_Pass_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Txt_Pass.TextChanged End Sub Private Sub Btn_Aceptar_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btn_Aceptar.Click Usuario = "VILLALON" contraseña = "VILLALON" If Txt_User.Text = Usuario And Txt_Pass.Text = contraseña Then 1