Adverbs which are used for asking questions are called interrogative adverbs. There are several different kinds of interrogative adverbs.

Interrogative Adverbs of Time

Examples are: when, how long, how early, how soon etc.

When will you finish this job?
How long will you stay here?
How often do you visit them?
How soon can you begin work?

Interrogative adverbs of Place

Where do you live?
Where has she come from?
Where can I find him?

Interrogative adverbs of number

Examples are: how many, how often, how much

How many students are there in the class?
How often does the committee meet?

Interrogative adverb of manner

Examples are: how

How did you arrive at the conclusion?
How are you doing?
How was the experience?
How did you do it?

Interrogative adverbs of degree or quantity

Examples are: how much, how far, how high etc.

How much did you pay?
How far can you go?
How much more do you want?

Interrogative adverbs of reason

Example: why

Why are you crying?
Why did you quit?
Why do you hate her?
Why do you want to go there?

Relative Adverbs

Read the sentence given below.

Do you know the place where the meeting will be held?

In the sentence given above, where is an adverb as it modifies the verb will be held. It is also a relative as it connects the two clauses of the sentence and at the same time refers back to its antecedent place. Where is therefore called a relative adverb. A relative adverb connects an adjective clause to the main clause.

That was the reason why I decided to resign.

Here why is an adverb as it modifies the verb decided to resign. It is also a relative as it connects the two clauses of the sentence and at the same time refers back to its antecedent reason. Why is therefore called a relative adverb because it connects the adjective clause ‘why I decided to resign’ to the main clause ‘that was the reason’.

More examples are given below.

This is the place where the murder was committed.

Notes:

The relative adverb when can be replaced by in which/on which; where can be replaced by in which/at which; why can be replaced by for which.

I don’t know the place where he lives. (= I don’t know the place at which he lives.)

I don’t know the reason why she hates me. (= I don’t know the reason for which she hates me.)
I still remember the day when he returned home. (= I still remember the day on which he returned home.)