Relative Clause | who, whom, whose

Question

Is it true that "who", "whom, and "whose" can only be used for humans? If it's true, then are these sentences correct?

"He bought a car which runs fast"

"He was wearing a cap which was black"

Answer 1

"He bought a car which runs fast" & "He was wearing a cap which was black"?

These are both correct, but probably should be punctuated with a comma before "which", or the relative pronoun "that" could have been used.

You should not use "a car who runs fast", except as poetic personification - rhetorically pretending that a car is a person.

You might see "a dog who runs fast", since we often treat pets as people.

Answer 2

Is it true that "who", "whom, and "whose" can only be used for humans?

You can use whose as a relative pronoun for inanimate objects, as in "The tree, whose leaves were brown..."

Yes, we would say "The tree which had brown leaves", but English doesn't have a relative pronoun like "which's", so we use whose for both people and inanimate objects.

Who and whom are only used for people, or sometimes animals and inanimate objects that we are treating like people.

If it's true, then are these sentences correct?

Yes, they are both correct. I'm not sure how that is related to your first question, since they could be correct whether the answer to the first question was "yes" or "no".

Answer 3

The sentences are correct.

He bought a car which runs fast.

He was wearing a cap which was black.

Who refers to people and which refers to things. We can use that instead of 'who' or 'which'.

He bought a car that runs fast.

He was wearing a cap that was black.

[ The man who came here yesterday is my friend. or The man that came here yesterday is my friend.

I know the man who came here yesterday. or I know the man that came here yesterday. ]