The difference between one and more than one matters in real life. "I have a child" and "I have children" are different families. "Send me the file" and "Send me the files" are different requests, and at work the wrong one wastes time. English marks this difference on the noun itself, so listeners expect it. If you say "three childs" or "two mans", people understand, but the mistake is loud — these are some of the most common words in the language.

Plurals also control the rest of the sentence. A plural noun needs "are", "were", "these", "those" and plural pronouns. When the noun form is wrong, verbs and pronouns often go wrong with it, and one small slip becomes three. Getting plurals right makes your whole sentence stand up straight.

The regular rule is simple: add "-s" to the noun. "Book" becomes "books", "phone" becomes "phones", "apple" becomes "apples". Most English nouns follow this rule, so it is your default. In speech, the "-s" sounds like /s/ after quiet sounds ("cats"), /z/ after voiced sounds ("dogs"), and /iz/ after hissing sounds ("buses") — but you do not need to think hard about this; it comes naturally with practice.

Spelling changes a little in three cases. After "-s, -x, -ch, -sh", add "-es": "bus → buses", "box → boxes", "watch → watches", "dish → dishes". After a consonant plus "-y", change "y" to "ies": "city → cities", "baby → babies" — but after a vowel plus "-y" just add "-s": "day → days", "key → keys". A few "-f/-fe" words switch to "-ves": "knife → knives", "leaf → leaves", "wife → wives".

Then there is a small famous group of irregular plurals that you must simply memorise, because they come from old English: "man → men", "woman → women", "child → children", "person → people", "foot → feet", "tooth → teeth", "mouse → mice". These words never take "-s". "Childs", "mans", and "foots" do not exist. The good news: the list is short, and these are everyday words, so you will hear the correct forms all the time.

A few nouns do not change at all: "one sheep, two sheep", "one fish, two fish", "one deer, two deer". And some nouns are already plural in meaning: "people" takes a plural verb ("People are waiting"), and "clothes", "glasses", and "trousers" have no singular form — you say "a pair of trousers" for one item.

Finally, remember that the plural spreads through the sentence. Say "This book is mine" but "These books are mine". With irregular plurals the same applies: "The children were happy", "Those men work here". When you make a noun plural, quickly check the words around it — "this/these", "is/are", "was/were" — and make them agree.

1. 1. The two women in the photo are my aunts.

   "Women" is the irregular plural of "woman" — no "-s".

2. 2. My feet hurt after the long walk.

   "Foot" becomes "feet"; the vowel changes instead of adding "-s".

3. 3. How many people are coming to dinner?

   "People" is the everyday plural of "person" and takes "are".

4. 4. The dentist checked all my teeth.

   "Tooth" becomes "teeth" — another vowel-change plural.

5. 5. We need three boxes for these old clothes.

   "Box" ends in "-x", so the plural adds "-es": "boxes".

6. 6. Both buses to the airport were full.

   "Bus" adds "-es", and plural "buses" needs "were", not "was".

7. 7. She has visited many cities in Europe.

   Consonant + "y" changes to "-ies": "city → cities".

8. 8. I took two days off last week.

   Vowel + "y" just adds "-s": "day → days", not "daies".

9. 9. The knives are in the top drawer.

   "Knife" changes "-fe" to "-ves" in the plural.

10. 10. The farmer has one hundred sheep.

    "Sheep" stays the same in singular and plural.

11. 11. Are those men waiting for the same train?

    In questions too, "man" must become "men" for more than one.

12. 12. There aren't any tomatoes for the salad.

    Nouns ending in "-o" often add "-es": "tomatoes", "potatoes".

13. 13. My glasses are on the kitchen table.

    "Glasses" (for your eyes) is always plural and takes "are".

14. 14. A mouse ran across the floor, then two more mice appeared.

    "Mouse → mice" is irregular; you hear both forms here.

15. 15. These children aren't tired yet.

    "These" and "aren't" agree with the irregular plural "children".

The classic mistake is adding "-s" to an irregular noun: "three childs", "two mans", "five persons" in everyday talk. English already has special plurals for these words: "three children", "two men", "five people". The "-s" versions fail because these old words never joined the regular rule. Since "child", "man", "woman", and "person" are among the most used nouns in English, learning their plurals by heart pays off immediately.

The second mistake is doubling the plural: "childrens", "peoples", "feets". Learners feel the word needs an "-s" to sound plural, but "children", "people", and "feet" are already plural. "The childrens are outside" is wrong; say "The children are outside". If the word is on the irregular list, it never also takes "-s". (You may see "peoples" in books, but there it means "nations" — a different, rare meaning.)

The third mistake is forgetting agreement around the plural. Learners write "These book is cheap" or "The children was playing". Wrong pairings like this break the sentence even when the noun itself is right. Match in threes: "this book is" / "these books are" / "the children were". When you say a plural noun, let "these", "are", and "were" follow it like a team.

• Default rule: add "-s"; add "-es" after -s, -x, -ch, -sh.
• Memorise the big seven: men, women, children, people, feet, teeth, mice.
• Irregular plurals never take an extra "-s" — no "childrens", no "feets".
• Consonant + y turns into "-ies" (cities); vowel + y just adds "-s" (days).
• Plural noun, plural partners: these, those, are, were.
• Say "a pair of" for trousers, jeans, glasses, and scissors.