AndrewRitchie，inventoroftheBromptonfoldingbicycle，oncesaidthattheperfectportablebikewouldbe“likeamagiccarpet…Youcouldfolditupandputitintoyourpocketorhandbag”．Thenhepaused：“Butyou'llalwaysbelimi

　　AndrewRitchie，inventoroftheBromptonfoldingbicycle，oncesaidthattheperfectportablebikewouldbe“likeamagiccarpet…Youcouldfolditupandputitintoyourpocketorhandbag”．Thenhepaused：“Butyou'llalwaysbelimitedbythesizeofthewheels．Andsofarnoonehasinventedafoldingwheel．”

　　Itwasarare—indeedunique—occasionwhenIwasabletoputRitchieright．A19th-centuryinventor，WilliamHenryJamesGrout，didinfactdesignafoldingwheel．Hisbike，predictablynamedtheGroutPortable，hadaframethatsplitintotwoandalargerwheelthatcouldbeseparatedintofourpieces．AllthebitsfittedintoGrout'sWonderfulBag，aleathercase．

　　Grout’saim：tosolvetheproblemsofcarryingabikeonatrain．Nowdoesn’tthatsoundfamiliar?Groutintendedtofindawayofmakingabikesmallenoughfortraintravel：hisbikewasahugebeast．Andimportantly，thedesignofearlybicyclesgavehimanadvantage：inGrout’sday，tyresweresolid，whichmadethebusinessofsplittingawheelintofourseparatepartsrelativelysimple．Youcouldn'tdothesamewithawheelfittedwithaone-pieceinflated（充气的）tyre．

　　So，ina21st-centurycontext，istheideaofthefoldingwheeldead?Itisnot．ABritishdesignengineer，DuncanFitzsimons，hasdevelopedawheelthatcanbesquashedintosomethinglikeaslenderellipse（椭圆）．Throughout，thetyreremainsinflated．

　　WilltheyoungFitzsimons'sfoldingwheelmakeitintoproduction?Ihaven'tthefoggiestidea．Buthisinventivenessshowstwothings．First，peoplehavebeensayingformorethanacenturythatbikedesignhasreacheditslimit，exceptforgradualadvances．It'sassillyaconceptnowasitwas100yearsago：there'splentystilltogofor．Second，itisinthefieldoffoldingbikesthatweareseeingthemostinterestinginventions．Youcanbuyafoldingbikeforlessthan£1，000thatcanbeknockeddownsosmallthatitcanbecarriedonaplane—minuswheels，ofcourse—ashandbaggage．

　　Foldingwheelswouldmakeallmannerofthingspossible．HaveweyetgotthemagiccarpetofAndrewRitchie’simagination?No．Butit'sprogress．

　　1．WecaninferfromParagraph1thattheBromptonfoldingbike_________．

　　A．wasportable B．hadafoldingwheel