CyclingBothchildrenandadultsridebicyclesforfunandforexercise.Somepeopleusebicyclesfortransportationbecauseitislessexpensivethantravelingbycar.16___.Thesportofcyclingconsistsofracesthatareheldmostlyo

　　Cycling

　　Bothchildrenandadultsridebicyclesforfunandforexercise.Somepeopleusebicyclesfortransportationbecauseitislessexpensivethantravelingbycar. 16___.

　　Thesportofcyclingconsistsofracesthatareheldmostlyonroadsortracks. 17 .ThefirstrecordedraceintheUnitedStateswasheldin1878inBostonMassachusetts.ThemostfamousbicycleracetheTourdeFrancebeganin1903.CyclingisalsoapartoftheSummerOlympicGames.

　　Sportcyclingincludesroadracesformenwomenandchildren.Someracescovershortdistancesof2.5to3miles.__18 .Astageraceconsistsofaseriesofracesheldoverseveraldaysorevenweeks.

　　Timetrials(计时赛)areatypeofcompetitioninwhichcyclistsdonotracedirectlyagainsteachother.Insteadindividualcyclistsorteamsaretimedastheyrideseparatelyoveracertaindistance.__19__.Moststageracesincludetimetrials.

　　Severaltypesofbicycleracesareheldonanoval(椭圆形的)track.Thetrackmaybeeitherindoorsoroutdoors.Inthehigh-speedracescyclistscompeteagainsteachotheroverashortdistance.Thepursuit(追逐赛)isaneventinwhichcyclistsstartonoppositesidesofthetrackandtrytocatcheachother. 20 .Themotorcyclecutsthroughthewindwhichnormallyslowsabicycledown.Asaresultcyclistscangomuchfasterthantheycaninotherraces.

　　A.Ittakesthreeweekstocomplete.

　　B.Otherscoverhundredsofmiles.

　　C.Thecyclistorteamwiththefastertimewins.

　　D.Theworld’sbestriderscompeteinit.

　　E.Inamotor-pacedraceeachcyclistridesbehindamotorcycleormotorbike.

　　F.Othersusebicyclesfortransportationbecausebicyclesdonotpollutetheair.

　　G.Sportcyclingbeganin1868witharacenearParisFrance.