Study materials
You say one sentence and your listener nods politely without understanding a thing. You add three words, and the person becomes recognisable.
I met a man yesterday.
I met the man who fixed our roof.
That is what who, which and that are for. They attach a tail to a noun explaining exactly which person or thing you mean.
Who, which or that
The choice comes down to one question: are you talking about a person or about a thing.
| What you mean | Which word to take |
|---|---|
| people | who, and also that |
| things and animals | which, and also that |
The woman who works here is a doctor.
The book which I bought was expensive.
The bus that goes to the station is late.
That suits people and things alike, and in conversation it is what you hear most. When in doubt, take that and you cannot go wrong.
The pronoun is already the subject
Here is where the commonest mistake hides. Who or which does not merely join the halves: it acts as the subject of the second half itself.
The man who lives next door is a teacher.
I have a friend who speaks five languages.
So there is no need to add he or she as well: the subject is already in place.
When it can be dropped
Now the pleasant part. Sometimes the pronoun is not needed at all, and native speakers cheerfully leave it out.
The test is simple. Look at what comes straight after who, which or that. If it is a verb, the pronoun is compulsory. If it is a subject of its own, the pronoun can go.
The film that we watched was funny.
The film we watched was funny.
In the sentence about the neighbour nothing can be dropped: who is followed straight away by the verb lives, and without the pronoun the phrase falls apart.
Two small things: the preposition and the comma
In spoken English the preposition happily stays at the end of the clause. Ukrainian never does that, so the sentence feels unfinished at first.
The person who I spoke to was helpful.
This is the flat that we live in.
And about the comma. Sentences like these take none: the clause is there to identify the noun, not merely to add something to it.
The mistakes everyone makes
The first is putting a second subject after the pronoun.
The man who he lives next door... → The man who lives next door...
The second is using which for a person.
the girl which sings → the girl who sings
The third is dropping the pronoun where it is the subject.
The man lives next door is my neighbour. → The man who lives next door is my neighbour.
All three are caught by one glance at what follows the pronoun. A verb means the pronoun is carrying the subject. A subject of its own means the pronoun is only a guest and may leave.
Try it right now
Describe two people around you in English so that they could be recognised: one with who, the other with no pronoun at all.
Then do the same for an object on your desk. If you never added a stray he or it, the topic is yours.