研究生入学考试英语试题及参考答案

XX年研究生入学考试英语试题及参考答案 The human nose is an underrated tool. Humans are often thought to be insensitive

XX年研究生入学考试英语试题及参考答案 Thehumannoseisanunderratedtool.Humansareoften thoughttobeinsensitivesmellersparedwithanimals,1 thisislargelybecause,2animals,westandupright.This meansthatournosesare3toperceivingthosesmellswhich floatthroughtheair,4themajorityofsmellswhichstick tosurfaces.Infact 5,weareextremelysensitivetosmells,6wedonot generallyrealizeit.Ournosesarecapableof7human smellsevenwhentheseare8tofarbelowonepartinone million. Strangely,somepeoplefindthattheycansmellonetypeof flowerbutnotanother,9othersaresensitivetothe smellsofbothflowers.Thismaybebecausesomepeopledo nothavethegenesnecessarytogenerate10smellreceptors inthenose.Thesereceptorsarethecellswhichsense smellsandsend11tothebrain.However,ithasbeenfound thatevenpeopleinsensitivetoacertainsmell12can suddenlybeesensitivetoitwhen13toitoftenenough. Theexplanationforinsensitivitytosmellseemstobethat brainfindsit 14tokeepallsmellreceptorsworkingallthetimebutcan 15newreceptorsifnecessary.Thismay16explainwhywe arenotusuallysensitivetoourownsmellswesimplydo notneedtobe.Wearenot17oftheusualsmellofourown