Despitetheproliferationofotherfastermodesoftransportation,therailroadsremainthelargestcarriersofintercityfreightintheUnitedStates.
A、schemesBatsfly,ratherthanglide,andthusaretheonlymammalscapableoftrueflight.
Thefearofsmallpox,whichterrorizedtheeighteenthcentury,hasnoanalogy(likeness)today.
Someseaurchins海胆havevenomous(toxin)spines
Creamoftartar酒石,aweakacid,canbeaddedtoeggwhitestohelpthemfoam泡沫whentheyarebeaten
TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.