function nav(id)
{

if(id!=""){

      document.getElementById("tb1").style.display="none";  
	      document.getElementById("tb2").style.display="none";  
		      document.getElementById("tb3").style.display="none";  

	
	document.getElementById("lm1").src="images/k3_02.jpg";

	    document.getElementById("lm2").src="images/k1_03.jpg";
		 document.getElementById("lm3").src="images/k1_04.jpg";
      
	  if(id==1){
		  	document.getElementById("lm1").src="images/k1_02.jpg";
		  document.getElementById("tb1").style.display="inline"
		  }
	   if(id==2){
		   	document.getElementById("lm2").src="images/k2_03.jpg";
		 document.getElementById("tb2").style.display="inline"
		   }
	    if(id==3){
				document.getElementById("lm3").src="images/k3_04.jpg";
		document.getElementById("tb3").style.display="inline"
			
			}
	
	
	}	
	
}