1000年前,人类在尝试制造各种药物的过程中,More than 1,000 years ago people experimenting in a ____ made the discovery,
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偶然发现将硫磺,硝石,木炭,以一定的比例混合,便生产出火药。They found that if sulphur, charcoal and potassium nitrate were____, with a certain ____ the mixture would explode.
火药使军事武器从冷兵器时代开始向火器发展。Gunpowder changed the style of wars. The ____ ended and gunpowder-based weapons are now widely used.
600多年前,中国便有了原始火炮。More than 600 years ago ____ were used in China.
利用火药燃烧产生的推力发射炮弹。Cannon balls were ____ by the thrust of the huo yao explosion.