function show_intro(pre,pree,n,select_n,css) {
  for (i = 1; i <= n; i++) {
    var intro = document.getElementById(pre + i);
	var cha = document.getElementById(pree + i);
    intro.style.display = "none";
    cha.className=css + "2";
      if (i == select_n) {
        intro.style.display = "block";
		cha.className=css + "1";
       }
    }
 }
 function VoteClick(vote)
{
  for (i=0;i<vote.vote.length;i++){
    if (vote.vote[i].checked==true){
      return true;
    }
  }
  alert("请选择您的调查选项！");
  return false;
}