formación de los plurales en inglés invariant plural http://en.wikipedia.org/wiki/English_plurals wikipedia http://en.wikipedia.org/wiki/English_plurals many many others en:English plurals Wikipedia this wikipedia's got a pretty good overview the head English plurals http://en.wikipedia.org/wiki/English_plurals Wikipedia identical in both the singular and plural http://en.wikipedia.org/wiki/English_plurals http://en.wikipedia.org/wiki/English_plurals identical in both the singular and plural invariant plural