Therehavebeenmanygreatinventionsorthingsthatchangedthew...
問題詳情：Therehavebeenmanygreatinventionsorthingsthatchangedthewaywefirstgreatinventionwastheonethatisstillveryimportanttoday—themadeiteasiertocarryheavythingsandtotravellongdistance.Forhundredsofyear...