What are interrogative pronouns ?
An interrogative pronoun is a pronoun used in order to ask a question. Some of them refer only to people, like "who" and others refer to people and objects, etc like "what".
They do not distinguish between singular and plural, so they only have one form.Interrogative pronouns produce information questions that require more than a "yes" or "no" answer.
WHAT can be used to ask about objects or people.
What time is it?
What is your name?
What do you want?
WHICH can be used to ask about objects or people.
Which chair are you talking about?
Which jumper do you like?
Which is your mother?
WHO can be used to ask about people
Who are you?
Which is your mother?
Who has been sitting in my chair?
WHOSE can be used to ask about a possession relation.
Whose is this book?
Whose car did you drive here?
WHOM can be used to ask about people.It is less usual and more formal than "who"
Notice that whom is the correct form when the pronoun is the object of the verb, as in "Whom did you see?" ("I saw John.")
However, in normal, spoken English we rarely use whom. Most native speakers would say (or even write): "Who did you see?"
Whom did you phone?
For whom will you vote?
Either "which" or "what" can also be used as an interrogative adjective, and that "who," "whom," or "which" can also be used as a relative pronoun.
・The man whom she chose will do a wonderful job.
What are relative pronouns?
A defining relative clause states defining information about a person or a thing. It is used to define one object/thing or a person from another. Without this information the sentence would not be clear.
They are used to join two or more sentences and forming in that way what we call "relative sentences".
・ Relative pronouns replace the noun.
・Relative pronouns can refer to singular or plural, and there is no difference betweenmale and female.
・People who speak two languages are called bilingual.
In this example, the relative "who" introduces the relative sentence "speak two languages" that describes or gives more information about the noun "people".
Subject or Object ?(Relative pronouns)
We can use the relative pronouns "who" and "whoever" to refer to the subject of a clause or sentence,
and "whom" and "whomever" to refer to the objects of a verb, a verbal or a preposition.
"Whom" is very formal. The relative pronoun is optional.
"Who" (subject) and "whom" (object) are generally only for people.
Whose is for possession.
"Which" is for things.
"That" can be used for people and things and as subject and object in defining relative clauses (clauses that are essential to the sentence and do not simply add extra information).
When referring to more than one person, place, thing or idea use these compound relative pronouns.
・The three approaches, whichever works is fine, produce a more ambiguous picture of a man.
"Whichever" relates to the noun "approaches" and the information contained within the commas is additional, not critical information.
・Any excessive profits, whatever exceeded accepted limits, would attract the notice of representatives.
"Whatever" relates to the noun "profits" and the information contained within the commas is additional, not critical information.
The compounds of who, which, and what are whoever, whosoever, whomever,whomsoever,whichever, whichsoever, whatever, whatsoever,whosever, whosesoever.
Referring to people: Who, Whom, Whoever, Whomever
These pronouns take a different case depending on whether the relative pronoun is a subject or an object in the dependent clause.
Use the subjective case when these relative pronouns are the subject (initiating the action) of the dependent clause: Who, Whoever
・Negotiations were not going smoothly between the two leaders, who made no bones about not liking each other.
"Who" relates back to the noun "leaders" and is the subject of the dependent clause and the verb "made".
・Most workers, whoever was not employed by the auto manufacturer, toiled at one of the millions of little minnow companies.
"Whoever" relates back to the noun "workers" and is the subject of the dependent clause and the verb "was employed".
Use the objective case when these relative pronouns are the object (receiving the action) of the dependent clause: Whom, Whomever
・This is the approach taken by journalists, whom some consider to be objective.
*"Whom" relates back to the noun "journalists" and is the object of the verb "consider". The subject of the dependent clause is "some".
・The three representatives, whomever the committee chooses, should be at the meeting tomorrow.
"Whomever" relates back to the noun representatives and is the object of the verb "chooses". The subject of the dependent clause is "Committee".
Referring to a place, thing or idea: Which, That
When using relative pronouns for places, things or ideas, rather than determining case, the writer must decide whether the information in the dependent clause is essential to the meaning of the independent clause or simply additional information.
1:When information is critical to the understanding of the main clause, use That as the appropriate relative pronoun and do not set the information off by commas.
・Russian generals have delivered a message that is difficult to ignore.
"That" relates back to the noun "message" and is necessary for the reader to know what "message" the sentence is about.
・There is another factor that obviously boosts the reputation of both of these men.
"That" relates back to the noun "factor" and is necessary for the reader to know what "factor" the sentence is about.
2:When information is not critical to the understanding of the main clause, use "Which" as the appropriate relative pronoun and set the information off by commas.
・The toughest intramural fight of all for Clinton was the North American Free Trade Agreement, which he undertook a full year before the 1994 election.
"Which" relates back to the noun "agreement" and the information following it is not necessary for the reader to know what "agreement" the sentence is about.
・Clinton refused to head toward the center on affirmative action and abortion, whichare the two most sacred issues to the traditional liberal wing of the party.
"Which" relates back to the noun "affirmative action and abortion" and the information following it is not necessary for the reader to know what "affirmative action and abortion" the sentence is about.
What are indefinite pronouns ?
An indefinite pronoun does not refer to any specific person, thing or amount. It is vague and "not definite".
Note that many indefinite pronouns also function as other parts of speech. Look at "another" in the following sentences:
・He has one job in the day and another at night. (pronoun)
・I'd like another drink, please. (adjective)
Most indefinite pronouns are either singular or plural.
However, some of them can be singular in one context and plural in another. The most common indefinite pronouns are listed below, with examples, as singular, plural or singular/plural.
Notice that a singular pronoun takes a singular verb AND that any personal pronoun should also agree (in number and gender).
Example ・Each of the players has a doctor.
・I met two girls. One has given me her phone number.
Similarly, plural pronouns need plural agreement:
・Many have expressed their views.
List of English indefinite pronouns
・another – Thanks, I'll have another.
・anybody – Anybody can see the truth.
・anyone -anyone can see this
・anything-Anything can happen if you just believe
・each – From each according to his ability, to each according to his need.
・either – Either will do.
・enough – Enough is enough.
・less – Less is known about this period of history.
・little – Little is known about this period of history.
・much – Much was discussed at the meeting.
・neither – In the end, neither was selected.
・one – One might see it that way.
・other – One was singing while the other played the piano.
・plenty – Thanks, that's plenty.
・somebody – Somebody has to take care of it.
・someone – Someone should fix that.
・something – Something makes me want to dance.
・you (in informal usage, in the sense of "one") – You can understand why.
・both – Both are guilty.
・few – Few were chosen.
・fewer – Fewer are going to church these days.
・many – Many were chosen.
・others – Others can worry about that.
・several – Several were chosen.
・they (in informal usage, in the sense of "people in general") – They say that smoking is bad for you.
Singular or plural
・all – All is lost.
・any – Any will do.
・more – More is better.
・most – Most would agree.
・none – None of those people is my father. None of those people are related to me.
・some – Some of the cake has been eaten. Some of the biscuits have been eaten.
・such – Such is life.
this source from wikipedia.