For regular nouns, the plural form is created by adding the letter s to the end of the noun (noun, nouns). If the singular noun ends with s, x, ch, or sh, then es is added to form the plural (bus, buses; fox, foxes; arch, arches; wish, wishes). If the word ends with y, then the y is dropped and ies added (city, cities). No punctuation is ever used between the noun and the plural-s, even if the word is an acronym that ends with the letter s.
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