function qiehuan(num) {
    for (var id = 0; id <= 16; id++) {
        if (id == num) {
            if (document.getElementById("qh_con" + id) != null)
                document.getElementById("qh_con" + id).style.display = "block";
            if (document.getElementById("mynav" + id) != null)
                document.getElementById("mynav" + id).className = "nav_on";
        }
        else {
            if (document.getElementById("qh_con" + id) != null)
                document.getElementById("qh_con" + id).style.display = "none";
            if (document.getElementById("mynav" + id) != null)
                document.getElementById("mynav" + id).className = "";
        }
    }
}