The emery is a hard metallic substance.
金刚砂是非常坚硬的金属物质。
Beware of what you do with this dangerous substance.
你处理这些危险品时,可要当心。
Antitoxin is substance that acts against a poisonous substance and prevents it from having a harmful effect.
抗毒素是抵抗有毒物质并防止其产生有害作用的物质。