Since a personal pronoun is used instead of a noun, it must be of the same number, gender and person as the noun for which it stands.
- Those beggars are idle. They refuse to work for their living. (Here the pronoun they is of the same number and person as the noun beggars.)
- Alice is a beautiful girl. She is also very kind.
When a pronoun stands for a collective noun, it must be in the singular number if the collective noun is thought of a whole.
- The fleet has reached its destination.
- The jury will give its verdict in a few hours.
If the reference is to the individual members of the group, a pronoun standing for a collective noun must be plural in number.
- The jury are still debating the issue and will announce their individual opinions in a few hours.
When two singular nouns joined by and are preceded by each or every, the pronoun must be singular in number.
- Every man and every boy should be ready to defend his country.
When two singular nouns are joined by or, either…or or neither…nor, the pronoun should be singular in number.
- Neither Peter nor John has brought his book. (NOT Neither Peter nor John have brought their books.)
Good manners require that we should say:
- ‘You and I’ not ‘I and you’
- ‘You and he’ not ‘he and you’
- ‘He and I’ not ‘I and he’