function showDiv_01(whichOne) {
 var divs =["one","two","three","four"];
 for(var i=0; i<divs.length; i++)
     document.getElementById(divs[i]).style.display = 'none';
 document.getElementById(whichOne).style.display = 'block';
} 


function showDiv_02(whichOne) {
 var divs =["five", "six","seven","eight"];
 for(var i=0; i<divs.length; i++)
     document.getElementById(divs[i]).style.display = 'none';
 document.getElementById(whichOne).style.display = 'block';
}