"고양이가 커피를 마셔요."
Translation:The cat drinks coffee.
Drinks coffee, tea, anything else but never the water from the specially designated bowl!
The verb is 마시다 with a verb stem 마시. ㅓis added to the stem to build the plain style verb, then ㅣandㅓ combine to form ㅕ.
In Serbia, when little kids ask why they can't drink coffee, parents tell them (at least they used to) that kids shouldn't drink coffee, or they'll grow mustaches. Or a tail like a cat's. Maybe that's why I'm sort of okay with this sentence.