Question

THE NOUN The plural of nouns
The plural of nouns is formed by adding the ending –s/-es to the singular.
This ending is pronounced:
*[s] after voiceless consonants except sibilants
a lamp –
a lake –

*[z] after vowels and voiced consonants except sibilants
a train –
a name –
a sea –

*[iz] after sibilants
a place –
a rose –
a wish –
a bench –
a garage –
a page –

The plural of nouns is formed by adding the ending –es to the singular if the noun ends in:
1) -s, -ss, -sh, -ch, -tch, -x;
a bus –
a class –
a bush –
a lunch –
a watch –
a box –

2) –y preceded by a consonant (-y is changed into –i before the ending –es);
a story –
a fly –
a city –

3) –o preceded by a consonant.
a hero –
a tomato –
exceptions: a piano – pianos, a photo – photos

The plural of some nouns ending in –f or –fe is formed by changing f into v and adding the ending –es.
a wife –
a shelf –
a wolf –
a half –
a leaf –
a calf –
a knife –
a life –

But there some nouns where the letter –f is not changed.
a roof –
a chief –
a handkerchief –
a safe –
a belief –

If the singular ends in a voiceless –th preceded by a long vowel or a diphthong, in the plural the final voiceless –th is changed into a voiced one after which the ending –s is pronounced [z].
a path –
a mouth –
+ to this rule: a house–

But if –th is preceded by a consonant or a short vowel the ending is pronounced as voiceless.
a month –
a smith –

Some nouns form the plural by changing the root vowel without adding the ending.
a man –
a woman –
a foot –
a tooth –
a goose –
a mouse –

To the nouns below in the plural the ending –en is added:
a child –
an ox –

The plural of the nouns below is identical with the singular:
a sheep –
a deer –
a swine –
a fish –
a fruit –
(Fishes, fruits mean different kinds of fish, fruit.)

Some nouns borrowed from Latin and Greek keep the plural form of the language from which they have been borrowed.
a phenomenon –
a criterion –
an erratum –
a datum –
a memorandum –
a crisis –
a basis –
a radius –

The plural of compound nouns is formed by adding the ending –s/-es to the head-noun.
a daughter-in-law –
a school-mate –
a man-hour –
a man-of-war –

If both nouns in the compound noun are equal (there is no head-noun), both nouns are converted into the plural.
a man-doctor –
a manservant –
a woman-teacher –

If there is no noun in the compound, the plural ending is added to the last word of the compound.
a forget-me-not –
a merry-go-round –

There are nouns used only in the singular or only in the plural.
only in the singular (Rus + Eng):
Chalk, silver, peace, courage

only in the singular in English:
Advice, knowledge, information, money, progress, hair

only in the plural (Rus + Eng):
Tongs, spectacles, scissors, shears, trousers, scales

only in the plural in English:
News, goods, clothes, contents, wages

only in the singular in Russian:
экспорт – export (process), exports (amount, cost)
импорт – import (process), imports (amount, cost)

only in the plural in Russian:
Ворота – a gate, gates
Часы – a watch, watches
Сани – a sledge, sledges

With the ending –s both in the singular and plural (Rus + Eng):
Средство – a means, средства – means
Завод – a works, заводы – works