Hello,<br/><br/>1.The sun was shining <b>all day</b>.<br/><br/>2.The sun was shining <b>all the day</b>.<br/><br/>In most of the sentences we find only 'all day', but the grammar book I do refer has an entry like<br/><br/>all (the) day.<br/><br/>Does it mean 'the' is optional?<br/><br/>If something is optional, then we may use or may not use.<br/><br/>The (2) is correct or not?<br/><br/>Thanks.