A Preposition requires an Object in the Objective Case.
The noun or pronoun in the objective case after a preposition is said to be governed by it.
When a preposition is followed by an adjective without a noun, supply the noun and parse the preposition accordingly.
Keep to the right (hand).
The preposition is frequently omitted, particularly after verbs of giving and procuring, after adjectives of likeness or nearness and before nouns denoting time, place, price and measure.
When it is practicable to supply the ellipsis, the noun or pronoun is parsed as in the objective, governed by the preposition thus supplied. But when no such word can be snpplied, we say the noun is in the objective, expressing time, place, price and measure without any governing word.
Give (to) me a book.
Get (for) me an apple.
Like (to) his father.
Near (to) his home.
They traveled (through) sixty miles (in) a day.
A wall six feet high.
Subjects worthy (of) fame.
Books worth (worthy of) a dollar.
Sometimes one preposition immediately precedes another.
From before the altar.
The two prepositions in such cases should be considered as one just as in the case of the compound prepositions UPON and WITHIN.
Sometimes a preposition precedes an adverb as AT ONCE and FOR EVER. The two words should be taken together as in the preceding case and called an adverb.