Unit3theworldofscienceUsinglanguage現(xiàn)在完成時(shí)現(xiàn)在完成時(shí)表示過去的動(dòng)作或存在的狀態(tài)對(duì)現(xiàn)在造成的影響或結(jié)果，過去的這個(gè)動(dòng)作或狀態(tài)也有可能持續(xù)下去。用法：表示一個(gè)動(dòng)作剛剛結(jié)束或完成，但這個(gè)動(dòng)作所造成的狀態(tài)或影響依然存在，即表示過去的動(dòng)作對(duì)現(xiàn)在的影響或結(jié)果，強(qiáng)調(diào)現(xiàn)在的情況，常與副詞just,already（多用于肯定句或疑問句）,yet（常用于疑問句或否定句句尾）連用。表示從過去到現(xiàn)在曾經(jīng)發(fā)生過或經(jīng)歷過某事，表達(dá)一種經(jīng)驗(yàn)或經(jīng)歷，常與副詞ever，never，once，twice，before等連用。常與for或since連用。For后面接一段時(shí)間；since后接時(shí)間點(diǎn)或表示過去時(shí)間的時(shí)間狀語從句。特殊句型【This/That/Itisthefirst/second/third…timethat…】【This/That/Itisthe+形容詞最高級(jí)+名詞+從句】【Itis/hasbeen…since...(過去式)】

ThisisthefirsttimethatI______________(watch)theplay.ThisisthebestfilmthatI______________(see).It___________(be)sixyearssinceIcamehere.

havewatchedhaveseenhasbeen現(xiàn)在完成時(shí)練習(xí)一1、Duringthelastthreedecades,thenumberofpeopleparticipatinginphysicalfitnessprograms_____________(increase)sharply.2、Afterseveralyearsofobservation,theresearchgroup__________(arrive)attheconclusionthatlanguageacquisitionisfasterwhenstudentsareexposedtothesituationwhereitisspoken.3、Simon_____________(attend)hisfatherforsuchalongtimethatheunderstandsalmosteverygestureofhisfather’s.4、Itisthefirsttimethatthelocaleducationauthority________(make)suchstrictrequirementsongoing-to-schooltimeforprimaryandmiddleschoolstudents.5、Overthelastfewyears,thenumberofstudentsparticipatinginvolunteerprograms______________(increase)sharplyinourschool.hasincreasedhasarrivedhasattendedhasmadehasincreased6、Researchersbelievethatsince2010anaverageofnearly35,000elephants_____________(kill)annuallyonthecontinent.7、Withthehelpofhightechnology,moreandmorenewsubstances_______________(discover)inthepastyears.8、Inthepastfewcenturies，thelighthousesalongNorthCarolina’scoast__________________(recognize)assignsofsafetyfortravelersatsea.9、Icomplained

tothemanagerofthehotelaboutthepoorservicelastweek,butuptonow，I____________(receive)hisreply.havebeenkilledhavebeendiscoveredhavebeenrecognizedhaven'treceived10、Largequantitiesofwater,aswellassomeothertimelyhelpincludingamedicalteam_______________(offer)sincetheseriousdroughthitYunnanProvince.11、Morethanoneworker_________________（send）tothetrainingcentertoimprovetheirworkingskillsinthepastthreeyears.12、Since2011,thecountry___________(grow)morecornthanrice.13、Regularlyeatingoutseemsto_____________(become)commonformanyyoungpeopleinrecentyears.hasbeensenthasgrownhavebecomehavebeenoffered現(xiàn)在完成時(shí)練習(xí)二將下面劃線句子改為現(xiàn)在完成時(shí)被動(dòng)語態(tài)。Withinthenext80years,ourlivesmaybechanged

beyondrecognitionby3Dprinting.Ithasalready

affectedmanythingsinourlives,rightdowntothe

foodweeat.Forinstance,somerestaurantsinLondon

haveserved3D-printedhamburgerstocustomers.

Butperhapsthemostsignificantsuccessthatpeople

haveachievedtodateisinmedicine.Theyhavemade

humanbodyparts,includingabeatingheart,with3D

printingtechnology.Anditisnotjusthumanswho

arebenefiting-inBrazil,peoplehavegivenanew

3D-printedshelltoaturtleinjuredinaforestfire!參考答案：1.Manythingsinourliveshavealreadybeenaffected.2.3D-printedhamburgershavebeenservedtocustomersinsomerestaurantsinLondon.3.Butperhapsthemostsignificantsuccessthathasbeenachievedtodateisinmedicine.4.Humanbod