numerous; many; all kinds of; used to describe a great variety or large quantity

To heat a substance to remove impurities, extract a component, or strengthen it; to smelt, refine, or temper

steel; an alloy of iron and carbon that is tougher than cast iron and harder than wrought iron

numerous; many; all kinds of; used to describe a great variety or large quantity

To improve one's character, skills, or physical fitness through practice or experience; often confused with 练 liàn

steel; an alloy of iron and carbon that is tougher than cast iron and harder than wrought iron