what is the difference between Interrogative Pronouns and interrogative adjectives.
An interrogative pronoun is a pronoun used in order to ask a question. Often it has no antecedent because the antecedent is unknown. That is why the question is being asked!
In modern English there are five interrogative pronouns:
what, which, who, whom, and whose.
Note that all five words may also be used as relative pronouns. A relative pronoun may be found in a question; an interrogative pronoun is found only in a question.
In addition, these pronouns may take the suffixes -ever and -soever.
As their name suggests, interrogative adjectives are those adjectives that are used in questions. In Spanish, they take the same form as the interrogative pronouns, although only a few of the pronouns can be used as adjectives.
which dish would you like?
What people are going to come?
Interrogative pronouns are used in asking questions. The pronouns who, what and which are used as interrogative pronouns.
e.g. Who telephoned?
What did you say?
Which is your brother?
a. Direct questions
Interrogative pronouns can be placed at the beginning of a sentence in order to ask a question. Such questions can be referred to as direct questions.
In a direct question, when the interrogative pronoun is the subject of a verb, the verb follows the subject. In the following examples, the verbs are underlined, and the subjects of the verbs are printed in bold type.
e.g. What has happened?
Who has been invited?
In these examples, what is the subject of the verb has happened, and who is the subject of the verb has been invited. The presence of the interrogative pronoun transforms the statement into a question, and a question mark must be used.
When the interrogative pronoun is the object of the verb or the object of a preposition, inverted word order must be used, with the first auxiliary preceding the subject of the verb. In the case of verbs in the Simple Present or Simple Past, the auxiliary do or did must be used.
e.g. What do you mean?
Which did she choose?
What is he doing?
To what can one attribute their success?
In the preceding examples, the subjects you, she, he and one are preceded by the auxiliaries do, did, is and can. In the first three examples, what and which are the objects of the verbs. In the fourth example, what is the object of the preposition to.
An interrogative adjective asks a question about a noun. interrogative adjectives have to agree with the word they modify in gender and number.
An interrogative adjective ("which" or "what") is like an interrogative pronoun, except that it modifies a noun or noun phrase rather than standing on its own (see alsodemonstrative adjectives and possessive adjectives):
Which plants should be watered twice a week?
Like other adjectives, "which" can be used to modify a noun or a noun phrase. In this example, "which" modifies "plants" and the noun phrase "which paints" is the subject of the compound verb "should be watered":
What book are you reading?
In this sentence, "what" modifies "book" and the noun phrase "what book" is the direct object of the compound verb "are reading."