function doSubmit(){
	var contents = document.fm.content; 
	var checked = false;
	for(var i=0;i<contents.length;i++){ 
		if(contents[i].checked){
		    checked = true;
			break; 
		}
	}
	if(!checked){ 
		alert("请选择答案!");
		return false;
	} 
	document.fm.submit();
}