A Friend of Mine — English Grammar Exercises
my/mine, your/yours, their/theirs — know the difference
The Double Possessive: 'a friend of mine'
The double possessive (also called the post-genitive or 'of mine' construction) is a distinctive feature of English that learners often avoid or misuse. Learner corpus data shows that errors involving 'of + possessive' are most common at B1 level, with two recurring patterns: using the object pronoun ('a friend of me') or using the possessive adjective ('a friend of my') instead of the required possessive pronoun.
The Structure
Indefinite article + noun + of + possessive pronoun (mine / yours / his / hers / ours / theirs)
Is that a student of yours? (= one of your students)
Some friends of ours are coming tonight. (= some of our friends)
That brilliant idea of his saved the project. (= one of his ideas)
Why 'a my friend' Is Wrong
English does not allow a possessive adjective directly after an indefinite article. 'A my friend' violates the rule that adjectives cannot stack with possessives before a noun. The 'of' construction is the grammatical workaround: it allows indefiniteness (a/an/some/any) and possession to coexist.
Pronoun, Not Adjective, After 'of'
After 'of', always use the pronoun form. Compare: 'A photo of her' (= a photograph depicting her) vs 'A photo of hers' (= a photograph belonging to her). The difference is ownership vs depiction.
Common Mistakes
✗ Is it a photo of your? → ✓ Is it a photo of yours?
✗ I saw a friend of her. → ✓ I saw a friend of hers.
Frequently Asked Questions
What is the difference between possessive adjectives and possessive pronouns?
Possessive adjectives (my, your, his, her, its, our, their) come before a noun and modify it: 'Is this your bag?' Possessive pronouns (mine, yours, his, hers, ours, theirs) stand alone and replace the noun to avoid repetition: 'I forgot my umbrella. Can I borrow yours?' The key test: if a noun follows immediately, use the adjective form. If the noun is omitted, use the pronoun form. Note that 'his' and 'its' serve as both adjective and pronoun.
What does 'a friend of mine' mean, and why not 'a my friend'?
'A friend of mine' is the double possessive (or post-genitive) construction meaning 'one of my friends'. English does not allow a possessive adjective after an indefinite article: 'a my friend' is ungrammatical. The pattern is: indefinite article + noun + of + possessive pronoun (mine/yours/his/hers/ours/theirs). Compare: 'I bumped into a colleague of hers' (one of her colleagues). After 'of', always use the pronoun form, not the adjective: 'of mine', not 'of my'.
What is the difference between 'its' and 'it's'?
'Its' (no apostrophe) is the possessive adjective, showing that something belongs to it: 'The company changed its logo.' 'It's' (with apostrophe) is a contraction of 'it is' or 'it has': 'It's raining' (= it is raining); 'It's been a long day' (= it has been). The test: expand the contraction. If 'it is' or 'it has' makes sense, write 'it's'. If not, write 'its'. This is one of the most common spelling errors at B1–B2 level in learner corpora.
How do I use 'own' in English — 'my own', 'on my own', or 'of my own'?
'Own' always follows a possessive adjective and adds emphasis on exclusive or personal possession. Three patterns: (1) possessive + own + noun for emphasis: 'She has her own room' (not shared); (2) on + possessive + own = alone, without help: 'He did it on his own' (never 'by his own'); (3) a/some + noun + of + possessive + own = something that personally belongs to someone: 'They want a house of their own'. Note: 'an own car' is wrong — 'own' always needs a possessive adjective before it.