Air is around us. We can not see it, smell it, or taste it. But we can feel the wind blow. We can see the wind move waves on the water, clouds in the sky, and tree branches. Wind is moving air.
Without air we could not breathe. There could be no living plants or animals. Because sound travels through air, without air there would be silence. The movement of air can support a large, heavy plane.
Air is a mixture of gases and water vapor. The most important gases in the air are nitrogen and oxygen. 78 percent of the air is made up of nitrogen, and about 21 percent of oxygen. Almost all living things use the oxygen in air. Fire cannot burn without oxygen.
上一篇: 高一英语作文
新概念英语第一册 Lesson 71:He’s awful
新概念英语第一册 Lesson 101:A card from Jimmy
新概念英语第一册 Lesson 135: The latest report
新概念英语第一册 Lesson 123: A trip to Australia
新概念英语第一册 Lesson 51:A pleasant climate
新概念英语第一册 Lesson 137:A pleasant dream
新概念英语第一册 Lesson 43:Hurry up
新概念英语第一册 Lesson 75:Uncomfortable shoes
新概念英语第一册 Lesson 95:Tickets,please
新概念英语第一册 Lesson 53:An interesting climate
新概念英语第一册 Lesson 107:It’s too small
新概念英语第一册 Lesson 69:The car race 汽车比赛
新概念英语第一册 Lesson 83:Going on holiday
新概念英语第一册 Lesson 79:Carol’s shopping list
新概念英语第一册 Lesson 93:Our new neighbour
新概念英语第一册 Lesson 127:A famous actress
新概念英语第一册 Lesson 87:A car crash
新概念英语第一册 Lesson 131:Don’t be so sure
新概念英语第一册 Lesson 133:Sensational news
新概念英语第一册 Lesson 97:A small blue case
新概念英语第一册 Lesson 67:The weekend
新概念英语第一册 Lesson 113:Small change
新概念英语第一册 Lesson 47:A cup of coffee
新概念英语第一册 Lesson 77:Terrible toothache
新概念英语第一册 Lesson 89:For sale
新概念英语第一册 Lesson 73:The way to King Street
新概念英语第一册 Lesson 39:Don’t drop it
新概念英语第一册 Lesson 85:Pairs in the spring
新概念英语第一册 Lesson 49:At the butcher’s
新概念英语第一册 Lesson 63:Thank you,doctor