HOW TO PARSE PREPOSITIONS.
327. Since a preposition introduces a phrase and shows the relation between two things, it is necessary, first of all, to find the object of the preposition, and then to find what word the prepositional phrase limits. Take this sentence:—
The rule adopted on board the ships on which I have met "the man without a country" was, I think, transmitted from the beginning.—E. E. Hale.
The phrases are (1) on board the ships, (2) on which, (3) without a country, (4) from the beginning. The object of on board is ships; of on, which; of without, country; of from, beginning.
In (1), the phrase answers the question where, and has the office of an adverb in telling where the rule is adopted; hence we say, on board shows the relation between ships and the participle adopted.
In (2), on which modifies the verb have met by telling where: hence on shows the relation between which (standing for ships) and the verb have met.
In (3), without a country modifies man, telling what man, or the verb was understood: hence without shows the relation between country and man, or was. And so on.
The parsing of prepositions means merely telling between what words or word groups they show relation.