InthenortheasternUnitedStates,itrainsintermittently間歇地throughoutthespring.
A、steadilySolidgeometryhasenabledastronomerstocalculatethepositionsoftheheavenlybodiesrelativetooneanother.
Themegaphone(microphone)makesthevoicesoundlouderbecauseitpointssoundwavesinonedirectionandkeepsthemfromspreadingoutinalldirections.
Foodmustbemoistinordertohaveataste.
Cometsarestillregardedwithawebysomepeople.
Despitetheproliferationofotherfastermodesoftransportation,therailroadsremainthelargestcarriersofintercityfreightintheUnitedStates.
