This document discusses noun numbers (singular and plural) and rules for forming plurals in English. It covers 4 main rules:
1. Nouns ending in ch, sh, x, s, ss add "es" to form the plural.
2. Nouns ending in o add "es" to form the plural.
3. Nouns ending in a consonant + y drop the y and add "ies" to form the plural.
4. Nouns ending in f or fe add "ves" to form the plural.
There are exceptions to each rule. The document also discusses irregular plural forms and words that stay the same in both singular and plural. Exercises