Stopandlisten!Whatdoyouhear?Youmayhearmanydifferentsoun...
问题详情：Stopandlisten!Whatdoyouhear?Youmayhearmanydifferentsounds.Someofthosesoundsmaybenoise.Noiseisaloudorunwantedsound.Manykindsofmachines,suchasmotorcycles,jetplanes(喷气式飞机),farmtractorscancau...