英语六级考试听力基础辅导材料英语六级考试听力基础辅导材料Allthingsaredifficultbeforetheyareeasy.以下是小编为大家搜索整理的英语六级考试听力基础辅导材料，希望能给大家带来帮助!更多精彩内容请及时关注我们应届毕业生考试网!part1隧道与广播HowcomewecanhearFMlongerinatunnelthanAM?为什么在隧道中调频广播比调幅广播的信号要好一点?It'sbecauseFMstationstransmitathigherfrequencies.Theygenerallygofromeighty-eighttoone-hundred-and-eightmegahertz.That'soverahundredmillioncyclespersecond.这是因为调频广播台的传播频率要频繁些。通常在88到108兆赫。即每秒转1亿圈。Asaresult,asingleradiowavefromanFMstationisonlyafewmeterslong,aboutthesizeofacar.AnAMstationisputtingoutradiowavesthatarehundredsoftimesaslong!因此，调频广播电台发出的一个电波的长度只有几米，大概是一辆车的大小。而调幅广播站发出的电波长达几百米。Longwavelengthstendtobeabsorbedorblockedastheytrytoenterthesmallertunnel.Thehigher-energyandshorter-wavelengthwavesfromanFMstationaren'tabsorbedorblockedasmuch.Instead,theytendtobouncearoundandgetreflectedoffofsurfaces,muchliketheinsideofatunnel.在穿越隧道时，长的波长会被吞并阻碍。而来自调频广播高能量，波长又短的电波则不会被吞并或阻碍。相反的，它们会被隧道表面反射回来。Ofcourse,theyonlybouncesofar.Ifthetunnelislongenough,evenFMstationsfadeoutuntilyoucomeouttheotherend.当然，它们只会在某个区域内反弹。如果隧道太长的`话，即使是调频广播也会逐渐变弱直到驶出隧道。part2Congressfirstdealtwithissuesofsafetyandhealthintheworkplacein1890,whenlegislationwaspassedforsafetystandardsincoalmines.Overthenextseveraldecades,morecomplicatedmachineryandnewchemicalsenteredtheworkplaceyearly,posingnewhazardstoworkers.国会第一次处理职业安全与健康的问题是在1890年，当时国会立法通过了煤矿安全标准。在接下来的几十年里，每年都有更复杂的机器和新化学物质进入工作场所，给劳动者带来了新的危害。Bythelate1960s,anestimated14,000workersweredyingonthejobeachyear,andover2millionweresufferingdisablinginjuriesfromwork-relatedaccidents.Foryearsbusinessandlaborgroupswrangledovertheneedforfederallegislation.到20世纪60年代后期，据估计每年都有一万四千多名工人因工致死，还有超过两百万工人因工受伤或致残。多年来，工商界和劳动团体就联邦立法的需要一直争论不休。OpinioninCongresswasdeeplysplitoverwhatformlegislationmighttake,butin1970CongressfinallyapprovedtheOccupationalSafetyandHealthAct,whichwouldestablishtheOccupationalSafetyandHealthAgency,or"OSHA."OSHAquicklybecameoneofthefederalgovernment'smostdislikedagencies.国会内部在确定立法形式上发生了严重分歧，但最终于1970年批准通过职业安