Here are 5 easy rules and tips to help you avoid mistakes with English pronouns. For more comprehensive rules please look under the appropriate pronoun on our pronoun grammar pages.

1. A personal pronoun AGREES with the noun it replaces.

  • Those cars are nice. They  look expensive.
  • John works hard. He  will do well.
  • That woman is my teacher. Do you know her?
  • My friend and I are going shopping. Like to join us?

2. DO NOT place an adjective before a personal pronoun. A subject personal pronoun can have an adjective AFTER the verb. (Exceptions are fixed phrases like poor me, lucky you.)

  • NOT  handsome him, red them
  • NOT  beautiful she, dangerous it, clever they
  • She looked  beautiful.  It was  dangerous.  They are  clever.

3. Pronouns NEVER have an apostrophe ('). Do not add an apostrophe to possessive pronouns like hers, ours, theirs. (If you see an apostrophe, you are looking at a contraction.)

  • The red bag is hers  and the blue bag is ours. ( NOT The red bag is her's and the blue bag is our's.)
  • One must do it oneself. (NOT one's self)
  • He's finished. (contraction = He is)
  • It's started. (contraction = It has)

4. My  is NOT a pronoun . A pronoun replaces a noun. In "This is my bag" the word my describes bag  (it is a possessive determiner). In "This bag is mine" the word mine replaces  my bag (it is a real pronoun). The same is true of your, its, our, their - they are possessive determiners. His and her  can be pronoun OR possessive determiner.

  • Is this your  car? (possessive determiner)
  • Where are our  keys? (possessive determiner)
  • Jo sold his  car. (possessive determiner)
  • He took my hand in his . (possessive pronoun)
  • She loved her  work. (possessive determiner)
  • I agreed to wait for her . (personal pronoun)

5. DON'T put yourself first! It is good manners to put the other person before you. (This is not a question of grammar - just manners.)

  • My wife and I are going swimming. (NOT I and my wife are going swimming)
  • Ram, Tara and I went home. (NOT I, Ram and Tara went home)
  • This is for you and me. (NOT This is for me and you)
  • They took John and me to the beach. (NOT They took me and John to the beach)

sources : Original Link