php导出excel中，若数据库一列内容中存在换行，则在excel中对应换成多行，怎么解决

<?php <br />//验证是否已登录<br />include 'remember_password.php';<br />	header("Accept-Ranges: bytes");<br />	header("Content-type: application/vnd.ms-excel");<br />	header("Content-Disposition: attachment; filename=".$filename);<br />	include("connect.php");<br />	$sql="select * from specific_step";<br />	$query = mysql_query($sql);<br />	echo "序号\t业务名称\t操作步骤\t备注\t录入人\t录入日期";<br />	while($row = mysql_fetch_array($query)){<br />		echo "\n";<br />		echo $row['serial_number']."\t".$row['name']."\t".$row['step']."\t".$row['other']."\t".$row['input_name'].<br />		"\t".$row['input_date'];<br />	}<br />?>

header("Accept-Ranges: bytes");<br />header("Content-type: application/vnd.ms-excel");<br />header("Content-Disposition: attachment; filename=".@$filename);<br /><br />$ar = array(<br />  "abcd<br />123",<br />  "再来一段<br />换行<br />再换行"<br />);<br />echo "序号\t备注\n";<br />foreach($ar as $k=>$v) {<br />  echo "$k\t\"$v\"\n";<br />}