interrogative adverbs used like interrogative pronouns

Question

Why are the interrogative adverbs "where" and "when" used like interrogative pronouns in the sentences below?

Where are you from? From when to when did you live there? Since when is Jane your sister?

Answer 1

"Where" is commonly used in questions about location. It is also used in statements about location:

Where did you put the book?

New York is where I met John.

I know where I am going.

The road goes ever on and on, down from the door where it began.

In many ways "where" stands for a place, just a a pronoun stands for a person. It can stand for an unknown place in a question, or a known place refered to in the same text.

"When" fulfills a similar role for a time or date.

When do you plan to arrive?

I knew that I was in trouble when I saw the gang.

I don't know when i will be able to visit.

"When" is used to stand for a point in tiem, just as "where" stands for a place, or 'who" for a person.