托福备考阅读试题练习.docx

托福备考阅读试题练习

托福备考阅读精选试题练习2017 对于学了许多而对他们无用的词汇的`人们，或学许许多多词汇而不能运用的人们，好象具有一大箱的工具而不能使用的木工一样，比不上一个工具少而能使用自如的木工。以下是小编为大家搜索整理的托福备考阅读精选试题练习2017，希望能给大家带来帮助!更多精彩内容请及时关注我们应届毕业生考试网! Whatunusualoruniquebiologicaltraitledtotheremarkablediversificationandunchallengedsuccessoftheantsforever50millionyears?Theanswerappearstobethattheywerethefirstgroupofpredatoryeusocialinsectsthatbothlivedandforagedprimarilyinthesoilandinrottingvegetationontheground.Eusocialreferstoaformofinsectsocietycharacterizedbyspecializationoftasksandcooperativecareoftheyoung;itisrareamonginsects.Richlyorganizedcoloniesofthelandmadepossiblebyeusocialityenjoyseveralkeyadvantagesoversolitaryindividuals. Undermostcircumstancesgroupsofworkersarebetterabletoforageforfoodanddefendthenest,becausetheycanswitchfromindividualtogroupresponseandbackagainswiftlyandaccordingtoneed.Whenafoodobjectornestintruderistoolargeforoneindividualtohandle,nestmatescanbequicklyassembledbyalarmorrecruitmentsignals.Equallyimportantisthefactthattheexecutionofmultiple-steptasksisaccomplishedinaseries-parallelsequence.Thatis,individualantscanspecializeinparticularsteps,movingfromoneobject(suchasalarvatobefed)toanother(asecondlarvatobefed).Theydonotneedtocarryeachtasktocompletionfromstarttofinish—forexample,tocheckthelarvafirst,thencollectthefood,thenfeedthelarva.Hence,ifeachlinkinthechainhasmanyworkersinattendance,aseriesdirectedatanyparticularobjectislesslikelytofail.Moreover,antsspecializinginparticularlaborcategoriestypicallyconstituteacastespecializedbyageorbodyformorboth.Therehasbeensomedocumentationofthesuperiorityinperformanceandnetenergeticyieldofvariouscastesfortheirmodaltasks,althoughcarefulexperimentalstudiesarestillrelativelyfew. Whatmakesantsunusualinthecompanyofeusocialinsectsisthefactthattheyaretheonlyeusocialpredators(predatorsareanimalsthatcaptureandfeedonotheranimals)occupyingthesoilandgroundlitter.Theeusocialtermitesliveinthesameplacesasantsandalsohavewinglessworkers,buttheyfeedalmostexclusivelyondeadvegetation. 1.Whi