Unit1 Nature New Words词汇表 essential a. absolutely necessary;vitally necessary 必要的，重要的，本质的 nitrogen a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas 喷 vapor n. a visible suspension in the air of particles of some substance 蒸汽 inert a. havingonly a limited ability to react chemically;chemically inactive 惰性的 the act of liberating someoneor something;a process that liberates or 释放 to liberate or discharge something 释放 substance n. that which has mass and occupies space 物质 smog n. air pollution by a mixtureof smoke and fog 烟雾 ozone n. a colorless gas (03)soluble in alkalis and cold water 臭氧 wel-being n. a contented state of being happy,healthy and prosperous 幸福。安康 a tiny piece of anything;a body having finite mass and internal structure but negligible dimensions 微粒，粒子 diesel n. an internal-combustion engine that burns heavy oil 柴油机，内燃机 Unit 1 Nature New Words词汇表 essential a. absolutely necessary; vitally necessary 必要的，重要的，本质的 nitrogen n. a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas 氮 vapor n. a visible suspension in the air of particles of some substance 蒸汽 inert a. having only a limited ability to react chemically; chemically inactive 惰性的 release n. the act of liberating someone or something; a process that liberates or discharges something 释放 v. to liberate or discharge something 释放 substance n. that which has mass and occupies space 物质 smog n. air pollution by a mixture of smoke and fog 烟雾 ozone n. a colorless gas （O3）soluble in alkalis and cold water 臭氧 well-being n. a contented state of being happy, healthy and prosperous 幸福，安康 particle n. a tiny piece of anything;a body having finite mass and internal structure but negligible dimensions 微粒，粒子 diesel n. an internal-combustion engine that burns heavy oil 柴油机，内燃机