학습하기 Passage 1 Gunpowder Gunpowder is a substance that burns rapidly and violently and is used as a propellant in some firearms. (A) It was invented in the 9th Century by Chinese alchemists. (B) However, the early recipes used large amounts of nonflammable materials. (C) European explorers learned the recipe from the Chinese, modified it, and used it to create new weap..