var num = 11; //this is number of content divs you have
function showContent()
{
	for(var i = 1; i < num + 1; i++)
	{
		document.getElementById('sc'+i).style.display = 'none';
	}
	if(document.forms[0].dropdown.options[document.forms[0].dropdown.options.selectedIndex].value != "none")
	{
		document.getElementById(document.forms[0].dropdown.options[document.forms[0].dropdown.options.selectedIndex].value).style.display = 'block';
	}
}
onload = function()
{
	for(var j = 1; j < num + 1; j++)
	{
		document.getElementById('sc' + j).style.display = 'none';
	}
}