A few rules to note when writing or speaking English

1. The words each and every are used when referring to individual elements of a set and are always followed by a singular noun (e.g., Each/every car was tested).
2. The adjective few is always followed by a plural noun (e.g., Few people understand the difference).
3. Adjectives always remain singular, even when followed by a plural noun, e.g., antibiotic (not antibiotics) substances.
4. Nouns that end with -is are usually pluralized by replacing -is with -es. For example, the plural of thesis is theses.
5. For nouns ending with –s, –sh, -ch, -o, or –x, plurals are formed by adding –es to the singular. For example, dress – dresses, mango – mangoes, brush – brushes, match – matches, box – boxes. However, the plural of piano is pianos, not pianoes.
6. For nouns ending with –y, preceded by a consonant, plurals are formed by changing –y to –ies. For example, body – bodies, lady – ladies, city – cities.
7. For nouns ending with –f or –fe, plurals are formed by changing –f or –fe to –ves. For example, wife – wives, leaf – leaves, loaf – loaves, knife – knives. However, the plural of chief is chiefs, not chieves.