"What is the largest harbor in Brazil?"

Translation: Kio estas la plej granda haveno en Brazilo?

[ChadScherr]

Since it's really asking which harbor in Brazil is largest, shouldn't this be "kiu"? Sometimes this rule seems very strict, so it's hard to know correct usage.

[mizinamo]

That would be "Which is the largest harbor in Brazil?", i.e. "Which (harbor of the harbors there)".

So, not an exact translation of the English sentence, but the meanings are, of course, very close.