英语六级听力考试冲关训练英语六级听力考试冲关训练Nothingisimpossibletoawillingheart.以下是小编为大家搜索整理的英语六级听力考试冲关训练，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!part1ScoopThatPoop我好“无辜”的Actually,dogpoopturnsouttohaveaprettybigenvironmentalimpact.IfyouthinkthattwoinfivehouseholdsintheU.S.haveatleastonedogandthataboutfortypercentofAmericansdon'tcleanupaftertheirpooches,well,allthatpoopreallyaddsup.Infact,it'swhatscientistscalltheFidohypothesis.狗狗便便严重污染环境。如果美国2/5家庭就养一只狗狗且当中大约40%的主人不收拾狗狗的便便。所有这些便便加起来也就是科学家说的.“狗狗”假说。(Fido是对狗狗通用的称呼)。Hey,mydog'snameisFido.我的狗狗就叫Fido。Theyconjecturethatalotofthatwasteendsupinwaterways.Recentstudies,infact,suggestthatdogsareinthirdorfourthplaceonthelistofcontributorstobacteriainwater.Talkaboutgross—fecalmatterisfullofdisease-causingbacterialikeE.Coli,salmonella,andgiardia.科学家推想，水道阻塞的罪魁祸首就是这些便便。近日有研究表明，造成水里滋生细菌的“元凶”狗狗排第三或第四。令人作恶的这些细菌可以致癌，比如：大肠埃希菌、沙门氏菌、鞭毛虫Nowthatbacteria-trackingmethodshavegottenbetter,scientistsestimatethatinsomeareas,20to30percentofthebacteriainastreamcomesfromdogs.细菌源追踪技术的日臻完善，科学家估计，部分地区20%到30%的细菌是由狗狗造成的。Really?Thatcan'tbegood!真的吗?那可不妙!Andthethingis,pollutionfromdogsisrelativelyeasytocontrol.Allyouhavetodoisscoopwhentheypoop.其实，狗狗造成的环境污染相对来说很容易避免，你需要做的只是在将狗狗的便便铲干净。part2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