Ineed so examples of adverbs and prepositions.

English words that can function as prepositions and adverbs include the following:

about, above, across, after, along, around, before, behind, below, between, beyond, by, down, in, inside, near, on, opposite, out, outside, over, past, round, since, through, throughout, under, up, within, without.

Examples:

We marched one after the other. (preposition)

The marchers came first, and the floats came after. (adverb)

A hairy spider crawls across the dining table. (preposition)

This river has no bridge, so we have to swim across. (adverb)  

explanation: the peple who eat people are people who need people because all the people that eat people need people to eat, so they satisfy their needs by eating people