With lasers scientists can probe many physical processes, such as combustion, once beyond our ken.视野
A、understandingA
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Incalculatingthedailycalorierequirementsforanindividual,variationsinbodysize,physicalactivity,andageshouldbetakenintoaccount.
Themegaphone(microphone)makesthevoicesoundlouderbecauseitpointssoundwavesinonedirectionandkeepsthemfromspreadingoutinalldirections.
Alllivingorganisms,regardlessoftheiruniqueidentity,havecertainbiological,chemical,andphysicalcharacteristicsincommon.
DoubleEagleinthefirsttransatlanticballoon,wasgreetedbyavidcrowdsinFrance.
TheNativeAmericaninterpreterSacajaweawasavaluablememberoftheLewisanddarkexpeditionin1805.