The megaphone(microphone) makes the voice sound louder because it points sound waves in one direction and keeps them from spreading out in all directions.
B
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AlthoughtheCarbon14methodofdatingoldobjectsisnotfoolproof,itisthebestmethodavailableatpresent
InthenortheasternUnitedStates,itrainsintermittently间歇地throughoutthespring.
Eyespots,themostrudimentaryeyes,arefoundinprotozoan原生动物flagellates鞭毛虫,flatworms扁形虫,andsegmentedworms片段蠕虫.
HowmanypeopleareawarethatadancerwiththeNewYorkCityBallettypicallywearsoutaminimumoftwohundredpairsoftoeshoesperyear?