function Tab1(num) {
    for (var i = 1; i <= 2; i++) {
        document.getElementById("ftd" + i).style.background = "url()";
        document.getElementById("fdiv" + i).style.display = "none";
        document.getElementById("fimg" + i).style.display = "none";
    }
    document.getElementById("ftd" + num).style.background = "url(images/xxk.jpg)";
    document.getElementById("fdiv" + num).style.display = "block";
    document.getElementById("fimg" + num).style.display = "block";
}
function Tab2(num) {
    for (var i = 1; i <= 3; i++) {
        document.getElementById("std" + i).style.background = "url()";
        document.getElementById("sdiv" + i).style.display = "none";
        document.getElementById("simg" + i).style.display = "none";
    }
    document.getElementById("std" + num).style.background = "url(images/xxk.jpg)";
    document.getElementById("sdiv" + num).style.display = "block";
    document.getElementById("simg" + num).style.display = "block";
}
function Tab3(num) {
    for (var i = 1; i <= 2; i++) {
        document.getElementById("ttd" + i).style.background = "url()";
        document.getElementById("tdiv" + i).style.display = "none";
       
    }
    document.getElementById("ttd" + num).style.background = "url(images/xxkwenti.jpg)";
    document.getElementById("tdiv" + num).style.display = "block";
   
}