The three words are relative pronouns than help in adding more information a specific noun.
They can also be regarded as relative clause indicator as each of them can be utilised to showcase a relative clause that is giving an additional description to an initial noun. Take for instance:
1. The counselor who just arrived from Togo has summoned every one of us.
Considering the above sentence, it is cleared that "who" introduces a clause "just arrived from Togo". The clause is classified as a relative one because it attaches more information to the noun phrase "The counselor".
It is possible to have more than one counselor in the utterance live context but the additional description given will help in revealing identity of the actual one talking about.
Consider these sentences:
2. The pen which I bought in from Dorcas yesterday had been stolen.
3. The woman whose children were taken to abroad last year has gone has been named for an award.
What do you understand about the sentences if you compare each of them with the first sentence above?
Let take them one after another:
"Who" is a pronoun that is used in giving more information about a human being who has been mentioned already in a sentence.
Consider:
4. Mary who got married to Smith last year has been transferred to another branch of our company.
It is also used to make enquiry about someone's identity especially name. In that essence, the sentence will be ended by question mark to indicate that is it a question that requires an answer
Consider:
5. Who is that big man?
6. Who exactly are you going with on the journey?
"Whom" is also a pronoun that has the same function as who. It usually assumes the position of object in sentence. In order to make a correct use of "whom", it should be preceded by a preposition such as to, on, for, with, in, against and so on.
It can be used to add more information about somebody just like who and it is also useful to ask questions. Note that "whom" must be preceded by a preposition.
Consider:
7. Janet, on whom I depend has failed me.
8. To whom did you give the credit card?
9. The chairman and doctors, with whom I worked were very kind to me
Should you use "whom" without any preposition, use "who" instead.
"Whose" is also a pronoun that adds more information to someone's identity but in terms of belongings or possession. It is used to ask question about ownership of something. It still performs the similar if compared with "who".
Consider:
10. Whose laptop is that Acer?
11. The manager, whose workers embark on indefinite strike has called on the workers' leaders for negotiation.
In sentences 10, it is noted that the Acer laptop belongs to someone whose identity remains unknown. "Whose" depicts belonging.
While in sentence 11, the workers are the manager's workers not someone else's. That is a belonging.
"Which" as who is used to attach more information to somebody, "which" is used to add more information to something.
In other words, it is used to find out from someone exact about one or more people or things from a group of people or things earlier mentioned in the conversational context.
Consider:
12. The result of the examination which I sat for last week has been released.
13. Which of the songs do you prefer?
14. Which girl are you referring to?
In regard to sentence 12, let us assume that the speaker wrote more than one examination at different points in time; while uttering the declaration above, the listener may need to ask "which of the examinations?". But since the additional description has been given "which I sat for last week" the question is no longer needed.
In regard to sentence 13, the speaker needs to know the exact song that the listener prefer.
To be updated soon.....
Olufajo Olulekan
Hello Reader, thanks for your visitation. I am Olufajo Olulekan, a blogger by passion, inspiring in helping people online with useful information. I usually blog on another different platform but create this blog to make people knowledgeable about English Language, Literature in English, and Literary Texts Summary and Analysis