1、必修3 Unit 4HOW LIFE BEGAN ON THE EARTHRead the explanation and speak out the word it explains.sudden and powerful;using force to hurt or attack violentadj.猛烈的；激烈的；强暴的harmfuladj.有害的atomn.原子existvi.存在；生存causing harm the smallest unit of any chemical element globen.地球；地球仪；球体to be,or to be real;to live,o
2、r to live in difficult conditions the world;a map of the world in the shape of a ball,which is fixed to a support and can be turned round at the same angle as the Earth turns in space;any ball-shaped objecttheoryn.学说；理论multiplyvi.&vt.乘；增加a formal statement of the rules on which a subject of study is
3、 based or of ideas which are suggested to explain a fact or eventto increase very much in number,or(in mathematics)to add a number to itself a particular number of times pron.&n.&adj.万亿；十亿billionthe number 1 000 000 000 with this result adv.因此；于是 thusoxygenn.氧a colourless gas that forms a large part
4、 of the air on Earth and which is needed by people,animals and plants to livethe mixture of gases around the Earth;a feeling that a place has of being pleasant and interesting or exciting atmospheren.大气层；气氛unlikeprep.不同；不像fundamentaladj.基本的；基础的different from forming the base,from which everything el
5、se develops(a length of)rings usually made of metal which are connected together and used for fastening,pulling,supporting,or limiting freedom,or as jewellery;a set of connected or related things any of various usually liquid substances which can react chemically with and sometimes dissolve other materials chainn.链子；连锁；锁链acidn.酸carbon dioxide二氧化碳the gas formed when carbon is burned,or when people or animals breathe out