function check_book(){
	if(document.k_book.mingzi.value==""){
		alert("名字必须填写！");
		document.k_book.mingzi.focus();
	    return false;
		}
  
	
	 if(document.k_book.code.value==""){
		 alert("身份证号码必须填写");
		 document.k_book.code.focus();
	     return false; 
		 }
 	 
	
	 if(document.k_book.tel.value==""&&document.k_book.mob.value==""){
		 alert("电话和手机必须填写一项！");
		 document.k_book.tel.focus();
	     return false; 
		 }
	
	}