Some verbs are very commonly used with reciprocal pronouns. For more information about these, see paragraphs 3.68 to 3.72.
1.143 Note that there is very little difference between each other and one another. They are both used to talk about two or more people or things, although some people prefer the use of each other when there are only two people or things, and one another when there are more than two.
each as subject
1.144 In formal written English, you can also use each as the subject of a clause and the other as the object of a clause or preposition. So, a more formal way of saying They looked at each other is Each looked at the other. Note that each is always followed by a singular verb.
Each accuses the other of lying.
Each is unwilling to learn from the experience of the others.
Each is also a determiner. For more information about this, see paragraph 1.243.
’s
1.145 You add ’s (apostrophe s) to each other, one another, and the other to form possessives.
I hope that you all enjoy each other’s company.
Apes spend a great deal of time grooming one another’s fur.
The males fight fiercely, each trying to seize the other’s long neck in its beak.
Joining clauses together: relative pronouns
1.146 When a sentence consists of a main clause followed by a relative clause introduced by who, whom, which, or that, these words are called relative pronouns.
Relative pronouns do two things at the same time. Like other pronouns, they refer to someone or something that has already been mentioned. At the same time they join clauses together.
For more information about relative clauses, see paragraphs 8.83 to 8.116.
who and whom
1.147 Who and whom always refer to people.
Who can be the subject of a relative clause.
…mathematicians who are concerned with very difficult problems.
In the past, whom was normally used as the object of a relative clause. Nowadays, who is more often used, although some careful speakers of English think that it is more correct to use whom.
…a man who I met recently.
He’s the man who I saw last night.
…two girls whom I met in Edinburgh.
Who is sometimes used as the object of a preposition when the object is separated from the preposition. Some careful speakers think that it is more correct to use whom.
That’s the man who I gave it to.
…those whom we cannot talk to.
Whom is almost always used when the object comes immediately after the preposition.
…Lord Scarman, a man for whom I have immense respect.
which
1.148 Which always refers to things. It can be used as the subject or object of a relative clause, or as the object of a preposition. Which is often used in British English to introduce relative clauses that refer to things.
…a region which was threatened by growing poverty.
…two horses which he owned.
…the house in which I was born.
Note that which cannot be used as the indirect object of a clause.
that
1.149 That refers to either people or things. It is used as the subject or the object of a relative clause or the object of a preposition. That is generally preferred in American English to introduce relative clauses that refer to things or to combinations of people and things.
…the games that politicians play.
He’s the boy that sang the solo last night.
It was the first bed that she had ever slept in.
That cannot be used as the indirect object of a clause.
whose
1.150 Whose shows who or what something belongs to or is connected with. Note that it cannot be used by itself, but must come in front of a noun.
…the thousands whose lives have been damaged.
There was a chap there whose name I’ve forgotten.
…predictions whose accuracy will have to be confirmed.
…sharks, whose brains are minute.
Note that whose is not restricted to people.
Asking questions: interrogative pronouns
1.151 One way of asking questions is by using an interrogative pronoun.
The interrogative pronouns are who, whose, whom, what, and which. They are used as the subject or object of a clause, or as the object of a preposition. Whose and which are also determiners. Other words, such as where, when, why, and how, are also used to ask questions.
Interrogative pronouns are not used as the indirect object of a clause.
Who was at the door?
‘There’s a car outside.’
‘Whose is it?’
Whom do you support?
What are you doing?
Which is best, gas or electric?
For more information about structures in which interrogative pronouns are used, see paragraphs 5.10 to 5.34.
1.152 Interrogative pronouns refer to the information you are asking for.
Who, whose, and whom are used when you think that the answer to the question will be a person.
‘He lost his wife.’ – ‘Who? Terry?’
He looked at the cat. Whose is it? Have you ever seen it before?
‘To whom, if I may ask, are you engaged to be married?’ – ‘To Daniel Orton.’
Which and what are used when you think that the answer to the question will be something other than a person.
Is there really a difference? Which do you prefer?