![Youmightbesurprisedtoknowthatbicycleshaveexistedforabou...]( "Youmightbesurprisedtoknowthatbicycleshaveexistedforabou...")
- 問題詳情：Youmightbesurprisedtoknowthatbicycleshaveexistedforabouttwohundredyears,butnooneissurewhofirstmadethispopulartwo-wheeledmachine.36Thefrontwheelwasmuchbiggerthanthebackone,andalsothereweren'tanypedals(踏板),Ridershadtomovethemselvesforwardbyp...
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