As Jimi Oke points out, it doesn't matter what letter the word starts with, but what sound it starts with. Since "standard" starts off by using a 'y' sound, it must choose 'a' in lieu of 'an'. Convey to us about this example sentence: The phrase in the example sentence https://petshopdubai35146.wikigop.com/1707470/top_guidelines_of_litter_alternatives_uae