TextBox appear depended on checkbox

<scriptlanguage="javascript"type="text/javascript"> 
           function forRentClicked(sender) {
 
                   var tb1 = document.getElementById('<%= TextBox4.ClientID %>');
                   tb1.style.display = sender.checked ? 'inline' : 'none';
           }
 
        </script>

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<asp:CheckBox ID="CheckBox1" runat="server"
                                    Text=" XS" onClick="forRentClicked(this)" Checked="True" />

 

<asp:TextBoxID="TextBox4"runat="server"Height="19px"Width="80%"CssClass="123"style="display:block;"></asp:TextBox>

 
how to set the default checkbox uncheck and the javascript can function ~ i want to create 5 check box while i'm click the text box appear~ thx