Eachyearthereisanincreasingnumberofcarsonroadsandstreet...
问题详情:Eachyearthereisanincreasingnumberofcarsonroadsandstreetsasmillionsofnewcarsandtrucksareproduced.OneoutofeverysixAmericansworksatputtingtogetherthepartsofcars,drivingtrucks,buildingroadsorfilli...