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1、Unit4 Languagepoints1.because, as, since与forbecause表示原因的语气较强，回答why问句的提问。如果原因不重要，或为人所知，一般用as或since。for表示原因的语气较because弱，类似补充说明，一般不用来回答why提出的问题。引导的从句不能放在句首，而且前面一般用逗号与主句分开。Nooneknowsexactlyhowtheearthbegan,asithappenedsolongago.Whatitwastobecomewasuncertai
2、nuntilbetween4.5and3.8billionyearsagowhenthedustsettledintoasolidglobe.2.betodo表示可能性3.settleinto迁入settledown安定下来Theearthbecamesoviolentthatitwasnotclearwhethertheshapewouldlastornot.4.violent adj.猛烈的，激烈的,强暴的violence 猛烈，暴力doviolenceto 损害violently 猛烈地The
3、ywereintimetoproducecarbon,nitrogen,watervapourand…5.intimetodosth./forsth.来得及……Shewillbebackintimetopreparedinner.intime及时终有一天ontime准时some time一些时间at times时常kill time消磨时间behind time落后all the time一直at a time一次at this time这时at that time那时at the same tim
4、e同时in no time立刻in the daytime在白天for a long time长时间at one time同一时期，同时地for the first time第一次from time to time不时地time and again反复地，不断地have a good time玩得高兴in time of在....的时候time的短语WaterhadalsoappearedonotherplanetlikeMarsbut,unlikeearth,ithaddisappearedlat
5、er.6.unlikeprep.与……不同；不像；非……的特征词语辨析：unlike，dislikeunlike(不像)是介词like(像)的反义词。dislike(不喜欢)是动词like(喜欢)的反义词。如：Aperson,unlikeamachine,isnotreplaceable.人和机器不同，是不可替代的。Hedislikesdogs. 他不喜欢狗。Itwasnotimmediatelyobviousthatwaterwastobefundamentaltothedevelopmentof
6、life.7.本句中It只起形式主语的作用,真正的主语是thatwaterwastobefundamentaltothedevelopmentoflife.用It做形式主语是因为that引导的从句较长,如果按照正常语序来安排的话就显得头重脚轻了。如:Itisnowonderthathehaspassedtheexam.Whatmanyscientistsbelieveisthatthecontinuedpresenceofwaterallowedtheearthtodissolveharmfulga
7、sesandacidsintotheoceansandseas.8.harmfuladj.有害的，伤害的harmv.&n.伤害harmfully伤害地harmless无害的harmlessly无害地beharmfulto对……有害doharmto对……有害dosb.harm对某人有害cometoharm受到损害cometonoharm未受到伤害Others,calledamphibians,wereabletoliveonlandaswellasinthewater.9.Othersotherthe
8、othertheothersanother10.aswellas…“(除...之外)也，又”,可连接并列的单词或短语Maryaswellasherparentslikestolistentomusic.Hegrowsflowersaswellasvegetables.aswell相当于too，一般放在句末。Heisaworker,andapoetaswell.aswellas相当于notonly…butalso，但两者在用法上有不同notonly…butalso侧重后
