Well, you check memory very briefly, make a quick scan, and it's awfully easy to say to yourself, Ring, Rang, Rung, and very hard to say to yourself, Pare, Park: they come more slowly.
적을까요? 자, 기억을 빨리 더듬어가며 쭉 훑어보면 Ring, Rang, Rung 같은 단어는 쉽게 떠오르지만 Pare, Park 같은 단어는 선뜻 생각이 잘 안나죠.