Themegaphone(microphone)makesthevoicesoundlouderbecauseitpointssoundwavesinonedirectionandkeepsthemfromspreadingoutinalldirections.
A、slitheringCreamoftartar酒石,aweakacid,canbeaddedtoeggwhitestohelpthemfoam泡沫whentheyarebeaten
Thewheelsofthefirstroadvehicleswerefashionedfromcrudestonedisks.
Despitetheproliferationofotherfastermodesoftransportation,therailroadsremainthelargestcarriersofintercityfreightintheUnitedStates.
Anoversight遗漏(miss,overslaugh)inproofreadingoftenresultsinprintederrors.
Withlasersscientistscanprobemanyphysicalprocesses,suchascombustion,oncebeyondourken.视野
