Nobody knows why these whales sing like troubadours

[keannu]

Is this "why" an interrogative or a relative adverb? They claim it is a relative pronoun as they think the reason is omitted. What is the standard to tell interrogative from relative adverb?

ex)Nobody knows why these whales sing like troubadours.

[5jj]

They claim it is a relative pronoun ....

Who are they?

If why introduces a direct question, it's interrogative. If it doesn't, it isn't.

Why do whales sing like troubadors? interrogative
Nobody knows why whales sing like troubadors. relative.

[keannu]

Who are they?

If why introduces a direct question, it's interrogative. If it doesn't, it isn't.

Why do whales sing like troubadors? interrogative
Nobody knows why whales sing like troubadors. relative.

You mean this is a relative adverb?
What about this one? "He asked me why I did it" or "When he came is not clear", "I don't know where he lives"
Is this also a relative adverb? In indrect questions, every "why, where, when" is all relative adverb? I'm a little bit confused.

[keannu]

You mean this is a relative adverb?
What about this one? "He asked me why I did it" or "When he came is not clear", "I don't know where he lives"
Is this also a relative adverb? In indrect questions, every "why, where, when" is all relative adverb? I'm a little bit confused.

The answers on the internet are all various, so it's hard to find the only one.

[Raymott]

Also, see my response in your other simultaneous thread about "why whales sing".
Would you prefer your answers here, or in the other thread?

[keannu]

Also, see my response in your other simultaneous thread about "why whales sing".
Would you prefer your answers here, or in the other thread?

Here!
The answers seem different from one another,

[Raymott]

Here!
The answers seem different from one another,

"Why" is a relative adverb when it introduces a relative clause.

http://www.ego4u.com/en/cram-up/grammar/relative-clauses
(Plenty of other pages for examples)

"When he came is not clear", "I don't know where he lives"
I'd call these relative adverbs too. They mean roughly: "The time when he came ..."; "... the place where he lives."
But, as I said elsewhere, "the time", "the place", "the reason" (for 'why'), "the manner" (for 'how') are usually not necessary. But they are the referents of the relative adverb.