Учебное пособие: Консультации по английской грамматике В помощь учителю иностранного языка

Compound nouns consisting of two separate components add -s for the plural number to the last component:

apple trees ocean liners

bank books post officers

car fares water jackets

leaf buds wind gauges

Note even: trouser pockets, pyjama jacket.

Proper names form their plurals by adding -s or -es: Adams, Georges, Henries, Dickenses. When a proper name is accompanied by a title, either the proper name or the title may be made plural:

Doctor Hills Mrs Thomases

Doctors Hill Mesdames Thomas

Letters, numerals and symbols are preferably pluralized by the addition of's:

three r's and four s's

my four's and five's

your etc.'s and i.e.'s

all M.P.'s

Some nouns have the same form for the singular and for the plural: cod, deer, grouse, sheep, trout, quail, aircraft;

dozen (twelve), score (twenty), stone (6,35 kg);

means, series, species, works, barracks, headquarters.

Some nouns have two plurals, each plural form differs in meaning from the other:

colour — цвет

colours — цвета

colours — флаг

cloth — ткань; лоскут

cloths — куски материи

clothes — платье, одежда

custom — обычай

customs — обычаи

customs — таможенные пошлины

die — штамп, матрица; игральная кость

dies — штампы, матрицы