// JScript 文件

function chang(d){
   
    if(d =="d1"){
        document.getElementById("d1").style.display="block";
        document.getElementById("d3").style.display="none";
        document.getElementById("d2").style.display="none";       
    }
    if(d =="d2"){
        document.getElementById("d2").style.display="block";
        document.getElementById("d1").style.display="none";
        document.getElementById("d3").style.display="none";       
    }
    if(d =="d3"){
        document.getElementById("d3").style.display="block";
        document.getElementById("d1").style.display="none";
        document.getElementById("d2").style.display="none";       
    }
}