设置radio的选中状态

   $("#s7").click(function () {
                var a = document.getElementById("s7");
                if (a.checked) { var b = document.getElementById("s9"); b.checked = true;}
                else
                {
                    var b = document.getElementById("s10");
                    var b1 = document.getElementById("s9");
                    b1.checked = false;
                    b.checked = false;
                }
            });