Private Sub cb1_CheckedChanged(sender As Object, _
        e As System.EventArgs) Handles cb1.CheckedChanged
 
        setchecked()
    End Sub
 
 
    Private Sub cb2_CheckedChanged(sender As Object, _
        e As System.EventArgs) Handles cb2.CheckedChanged
 
        setchecked()
    End Sub
 
 
    Private Sub setchecked()
        Dim res1 As String = "Res1"
        Dim res2 As String = "Res2"
        tx.Text = ""
        If cb1.Checked Then tx.Text = res1 & Environment.NewLine
        If cb2.Checked Then tx.AppendText(res2)
    End Sub