48. English often uses the preposition "of" between two words where
no idea of possession really exists, as "the city of Boston." Since
nouns used in apposition refer to the same thing, and are in the same
grammatical construction, Esperanto does not use a preposition:
La urbo Bostono estas granda, the city (of) Boston is large.
Mia amiko Johano estas alta, my friend John is tall.
Cxu vi ne konas min, vian amikon? do you not know me, your friend?