任何提示或帮助都会很棒。

<?xml version="1.0" encoding="UTF-8"?>
 <heading>
 The Twelve Days of Christmas
 </heading>
 
<song> //OxyGen highlights "<song>" as the error,but i'm not sure I understand.
    <Day ="One"> 
        <verse>
    On the first day of Christmas,my true love sent to me,a partridge in a pear tree.
        </verse>
    </Day>
 
    <Day="Two">
        <verse>
     On the second day of Christmas,my true love sent to me 
     Two turtle doves 
     and a partridge in a pear tree. 
        </verse>
    </Day>
 
     <Day="Three"> 
         <verse>
     On the third day of Christmas,my true love sent to me 
     Three French hens,two turtle doves 
     And a partridge in a pear tree.
         </verse>
     </Day>
 
     <Day="Four">
         <verse>
     On the fourth day of Christmas,my true love sent to me 
     Four calling birds,three French hens,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Fifth">
         <verse>
     On the fifth day of Christmas,my true love sent to me 
     Five golden rings. 
     Four calling birds,two turtle doves 
     And a partridge in a pear tree.
         </verse>
     </Day>
 
     <Day="Sixth">
         <verse>
     On the sixth day of Christmas,my true love gave to me 
     Six geese a-laying,Five golden rings. 
     Four calling birds,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Seventh">
         <verse>
     On the seventh day of Christmas,my true love gave to me 
     Seven swans a-swimming,six geese a-laying,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Eighth">
         <verse>
     On the eighth day of Christmas,my true love gave to me 
     Eight maids a-milking,seven swans a-swimming,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Ninth">
         <verse>
     On the ninth day of Christmas,my true love gave to me 
     Nine ladies dancing,eight maids a-milking,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Tenth">
         <verse>
     On the tenth day of Christmas,my true love gave to me 
     Ten lords a-leaping,nine ladies dancing,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Eleventh">
         <verse>
     On the eleventh day of Christmas,my true love gave to me 
     Eleven pipers piping,ten lords a-leaping,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
     <Day="Twelfth">
         <verse>
     On the twelfth day of Christmas,my true love gave to me 
     Twelve drummers drumming,eleven pipers piping,two turtle doves 
     And a partridge in a pear tree. 
         </verse>
     </Day>
 
 </song>