托福阅读试题考前辅导.docx

托福阅读试题考前辅导

2017年托福阅读试题考前辅导 治学有三大原则：广见闻，多阅读，勤实验。以下是小编为大家搜索整理的2017年托福阅读试题考前辅导，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! Moltingisoneofthemostinvolvedprocessesofabird'sannuallifecycle.Notwithstandingpreeningandconstantcare,themarvelouslyintricatestructureofabird'sfeatherinevitablywearsout.Alladultbirdsmolttheirfeathersatleastonceayear,anduponcloseobservation,onecanrecognizethefrayed,raggedappearanceoffeathersthatarenearingtheendoftheirusefullife.Twodistinctprocessesareinvolvedinmolting.Thefirststepiswhentheold,wornfeatherisdropped,orshed.Thesecondiswhenanewfeathergrowsinitsplace.Wheneachfeatherhasbeenshedandreplaced,thenthemoltcanbesaidtobecomplete.This,however,isanabstractionthatoftendoesnothappen:incomplete,overlapping,andarrestedmoltsarequitecommon. Moltrequiresthatabirdfindandprocessenoughproteintorebuildapproximatelyone-thirdofitsbodyweight.Itisnotsurprisingthatabirdinheavymoltoftenseemslistlessandunwell.Butfarfrombeingrandom,moltiscontrolledbystrongevolutionaryforcesthathaveestablishedanoptimaltimeandduration.Generally,moltoccursatthetimeofleaststressonthebird.Manysongbirds,forinstance,moltinlatesummer,whenthehardworkofbreedingisdonebuttheweatherisstillwarmandfoodstillplentiful.Thisiswhythewoodsinlatesummeroftenseemsoquiet,whencomparedwiththeexuberantchorusesofspring. Moltoftheflightfeathersisthemosthighlyorganizedpartoftheprocess.Somespecies,forexample,beginbydroppingtheoutermostprimaryfeathersoneachside(toretainbalanceintheair)andwaituntilthereplacementfeathersareaboutone-thirdgrownbeforesheddingthenextoutermost,andsoon.Othersalwaysstartwiththeinnermostprimaryfeathersandworkoutward.Yetotherspeciesbegininthemiddleandworkoutwardonbothsides.Mostducksshedtheirwingfeathersatonce,andremainflightlessfortwoorthreeweekswhilethereplacementfeathersgrow. 1.Thepassagemainlydiscusseshow (A)birdsprepareforbreeding (B)birdfeathersdifferfromspecies (C)birdsshedandreplacetheirfeathers (D)birdsareaffectedbyseasonalchanges 2.Theword"Notwithstanding"inline2isclosestinme