There are 9 parts of speech or word classes in English language:
– nouns
– pronouns
– determiners
– verbs
– prepositions
– adjectives
– adverbs
– conjunctions
– interjections

Nouns are a group of words that we use to name:
– people: man, woman, teacher, John, Mary
– animals: cat, rabbit, horse, elephant
– plants: palm tree, coconut trees, grass, wheat, corn
– places: home, office, town, village, England
– concrete objects: chair, table, ball, water, money, sugar
– abstract objects: truth, lies, happiness, sorrow, time, friendship

Determiners, prepositions and adjectives are related to the use of nouns.

– Determiners specify a limit to nouns.
I saw a cat.
‘A’ is a determiner.
‘Cat’ is a noun.

– Prepositions specify relations between two nouns.
The cat is under the bed.
‘Under’ is a preposition.
‘The cat’ and ‘the bed’ are nouns.

– Adjectives specify the condition, characteristic, emotion of nouns.
James is sick.
‘James’ is a noun.
‘Sick’ is an adjective.

James is happy.
‘Happy’ is an adjective.

We use determiners in front of nouns or noun phrases.
a cat
the cat
that person
two American citizens
all books
some information

We use interrogative determiners in questions to specifically ask certain things:
– what
– which
– whose

We use interrogative determiners ‘what’ to ask something specific of a noun.

What + noun

What food do you like?
What book did you buy yesterday?

We use interrogative determiners ‘which’ to confirm one thing/person or more from a group of some things/people.

Which + noun

Which course did you take last year?
Which employee talked to Mr. Tan yesterday?

We use interrogative determiners ‘whose’ to ask the owner of something or some things.

Whose + noun

Whose book is this?
= Who is the owner of this book?

Whose car is that?
= Who is the owner of that car?

We can use interrogative determiners with:
– singular countable nouns
Whose book is this?

– plural countable nouns
Whose books are those?

– uncountable noun
Whose money is this?