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科技论文中常用的两种时态是现在时和过去时。一般而言，在表述观察结果、已完成的行为及特定结论时应使用过去时。例如，描述实验结果时要使用过去时，因为实验已经结束，而你的结果尚未成为公认的“事实”。因此，那些主要涉及你自身工作的内容，如“摘要”、“材料和方法”以及“结论”部分都应使用过去时。例1aHighertemperaturesresultedinlessbudformation.bThethreeimagesweretakenabout90minutesapart.对于那些普遍认可的概念和观点用现在时表述。咨询白老师口口号1104734439已经发表的结果通常被视为“事实”。“前言”部分要使用现在时，因为其所介绍的是前人构建的知识。例2aThenewlydiscoveredplanetisatleastasbigasPluto.bMostregionswherethisproblemarisesbelongtocategoryX.如果用过去时描述已经发表的工作的结果，则表示你不认为该结果是“事实”，而仅仅是观察结果。例3Sultanobservedthatcertainspeciesofbacteriarespondtolightstimuli.该句描述的是一个已经完成的实验。因此“observed”使用了过去时，然而“respond”却使用了现在时，这是因为这部分句子表述的是事实，是发表过的、已经存在的知识。“讨论”部分是探讨你的工作与前人工作的关系，这部分最难写，期刊之家网做为优秀学术期刊杂志投稿发表论文指南性权威网站,通过期刊之家的Z2Z论文分检输送平台为优秀学术期刊推荐对口学术论文,提高论文发表命中率至93%以上,翟编辑办公QQ1452344485历时11年有效沉淀出畅通的论文发表绿色通道为学术论文发表到对口的学术期刊上提供了有力的时间保证,受到了广大作者朋友的青睐和相关杂志社领导的肯定;因为同时涉及现在时和过去时。记住，通常情况下，展现数据图表时用现在时，描述假说和原理时也用现在时。例4TheeffectofTXYadditionisshowninFigure5.当观察被重复进行或从过去持续到现在，则使用现在完成时。例5Xhasbeenofinterestforthepastthreedecades.只有一种情况使用将来时，就是你的实验计划于将来实施。未来的实验一般不会出现在研究论文中，但会出现在基金申请中。例6Wewillexamineifparalleluniversesexit.练习：下列各句应使用过去时还是现在时(如果答案不只一个，请解释原因)。1.Inourstudy,treesize__________(increase)withreductionofpesticides.2.Thelarvaofthemonarchbutterfly__________(feed)onmilkweed.3.Inourstudy,we__________(find)thattherearesignificantflatteningsofthePESalongthereactionPthwithincreasingclustersize,asFig.5__________(indicate).4.InastudybyFermi,thevibrationallevels__________(diverge)intotheso-calledFermidyad.5.Femalesofthisspecies__________(have)auniqueprojectionfromhedorsalpartofthethorax.6.RecentworkbydeValt(2001)__________(show)thatnematodes__________(reproduce)readilyinthelaboratory.7.Aphagemidconstructencoding2transgenesintandem__________(can)beusedtotransformE.colicells.8.Table3__________(show)thatinourstudy,polychaetes__________(be)mostabundantatdepthsof10to16m.9.Baumann(1997)__________(find)thatthisbacterium__________(is)highlysensitivetopH.10.We__________(observe)chemoattractionwithin30minofShhaddition.11.Identificationofrestrictionfactors__________(give)usmoreknowledgeofthehostcellrestrictionsystem.12.Ourresults__________(suggest)thattheAsn5glycosylationsite__________(play)acriticalroleinthefunctionoftheKCEN1protein.13.We__________(investigate)high-qualitysinglecrystalsofvanadiumoxide.14.We__________(do)notobserverodsinthediffractionpatternsbutinsteadwell-definedBraggspots,suggestingthatatleast10interatomiclayersinthesurface-normaldirection__________(be)contributingtotheinterferences.15.Coupledclimate-carboncyclemodels__________(suggest)thatAmazonforests__________(be)vulnerabletodroughts,butsatelliteobservations__________(show)agreen-upinintactevergreenforestsoftheAmazoninresponsetoashort,intensedroughtin2005.16.TheKavalueforβ-cellobiosyl(approaching103M-1)______(be)comparabletothatformanycarbohydrate/proteininteractions.17.Hundredsofspeciesofreef-buildingcorals__________(spawn)synchronouslyoverafewnightseachyear,andmoonlight_________(regulate)thisspawningevent.18.Arcticwindanomalies______(be)partofaglobal-scalepatternofhighlyunusualcirculationin2007,thecausesofwhich______(be)asyetunclear.19.Tomappathwaysofmotion,allobservedBraggdiffractionsofdifferentplanesandzoneaxes__________(beexamine)onthefemtosecondtonanosecondtimescale.20.ABSTRACT:Theaveragetranslationalenergy_____(be)significantlylowerthanexpectedforthecalculatedsurfacetemperature.21.SUMMARY:Inconclusion,we_____(find)significantdeviationsfromtheequilibriumbehaviorinfs-laserinduceddesorptionofCO/Ru.参考答案1.increased2.feed3.found…indicates4.diverged5.have6.showed…reproduce7.can8.shows…were9.found…is/was10.observed11.gives12.suggest…plays13.investigated14.did…are15.suggest…are…showed16.is17.spawn…regulates18.were…are19.wereexamined20.was21.found