function checkvalue_comment(){
	  if(document.comment1.user.value.length == 0 || document.comment1.user.value.length > 20){
	  	   alert("请输入姓名！");
	  	   document.comment1.user.value = "";
	  	   document.comment1.user.focus();
	  	   return false;
	  	}
   if(document.comment1.content.value.length == 0 || document.comment1.content.value.length > 200){
      alert("请输入评论内容！");
      document.comment1.content.value = "";
      document.comment1.content.focus();
      return false;
   }
   document.comment1.submit();
   document.comment1.user.value = "";
   document.comment1.content.value = "";
}