//lab
function lab2(tb1,dv1,tb2,dv2){
	var tb1=document.getElementById(tb1);
	var tb2=document.getElementById(tb2);
	var dv1=document.getElementById(dv1);
	var dv2=document.getElementById(dv2);
	tb1.className=tb2.className="off";
	dv1.style.display=dv2.style.display="none";
	tb1.className="on";
	dv1.style.display="";
	}
function lab3(tb1,dv1,tb2,dv2,tb3,dv3){
	var tb1=document.getElementById(tb1);
	var tb2=document.getElementById(tb2);
	var tb3=document.getElementById(tb3);
	var dv1=document.getElementById(dv1);
	var dv2=document.getElementById(dv2);
	var dv3=document.getElementById(dv3);
	tb1.className=tb2.className=tb3.className="off";
	dv1.style.display=dv2.style.display=dv3.style.display="none";
	tb1.className="on";
	dv1.style.display="";
	}