He-_only_ lost his book. (No one else lost a book.)
He _only_-lost his book. (He did nothing else with it.)
He lost _only_ his book. (He lost nothing else.)
He lost his _only_ book. (His single book.)
Certain adverbs and conjunctions are correlative (that is, _having a
mutual relation_) to one another. Be careful to use the proper
correlatives; as, He is esteemed _not only_ for his accomplishments,
_but also_ for his piety.