If we use a sentence like:

it is not very clear which man. We can make it clear like this:

Who links the relative clause (who is an English teacher) to the main clause (I know a man).

When we talk about people, we use that or who:

• I talked to the girl that (OR who) won the race.

When we talk about things or animals, we use that or which:

• I like the car that (OR which) won the race.

That, who, or which can be the subject of the relative clause, like this:

There is no other pronoun (e.g. it, they):

• NOT: That is the dog that it attacked me.

That, who, or which can be the object of the relative clause, like this:

There is no other pronoun (e.g. him, them):

• NOT: I man I saw him was very rude.

When that, who, or which is the object of the relative clause (e.g. The card which Ken sent), we can leave them out:

• The card Ken sent was very nice.
• The man I saw was very rude.

Now look at this sentence with whose:

• Susan is the woman whose husband is an actor. (= Her husband is an actor.)

We use whose in place of his, her, their, etc. We use it with people, countries and organisations, not things. It has a possessive meaning. Here is another example:

• The man whose dog bit me didn’t apologise. (= The man didn’t apologise. dog bit me.)