可汗阅读新增30篇(加天道水印）.pdf

可汗阅读可汗阅读 30篇篇（新增）（新增）天道教育 可汗阅读 23 篇（新增）天道教育 h t t p:/t i a n d a o e d u.co m/Level 2 Passage 41Level 2 Passage 54Level 2 Passage 67Level 2 Passage 710Level 3 Passage 613Level 3 Passage 716Level 4 Passage 419Level 4 Passage 522Level 4 Passage 625Level 4 Passage 728Level 2 Passage 231Level 2 Passage 334Level 2 Passage 437Level 3 Passage 440Level 4 Passage 343Level 2 Passage 546Level 2 Passage 649Level 3 Passage 452Level 3 Passage 555Level 4 Passage 358Level 2 Passage 461Level 2 Passage 564Level 3 Passage 567Part 1 SciencePart 2 Social SciencePart 3 HistoryPart 4 Literature天道教育 h t t p:/t i a n d a o e d u.co m/CONTINUE1ScienceQuestions 1-11 are based on the following passage.This passage is excerpted from David B.Wake and Vance T.Vredenburg,“Amphibians in Crisis.”2008 by The National Academy of Sciences of the USA.Amphibians have received much attention during the last decades because of a now-general understanding that a larger proportion of amphibian species are at a risk of extinction than those of any other taxon.*Why this should be has perplexed amphibian specialists.A large number of factors have been implicated,including most prominently habitat destruction and epidemics of infectious diseases;global warming also has been invoked as a contributing factor.What makes the amphibian case so compelling is the fact that amphibians are long-term survivors that have persisted through the last four mass extinctions.Paradoxically,although amphibians have proven themselves to be survivors in the past,there are reasons for thinking that they might be vulnerable to current environmental challenges and,hence,serve as multipurpose sentinels of environmental health.The typical life cycle of a frog involves aquatic development of eggs and larvae and terrestrial activity as adults,thus exposing them to a wide range of environments.Frog larvae are typically herbivores,whereas adults are carnivores,thus exposing them to a wide diversity of food,predators,and parasites.Amphibians have moist skin,and cutaneous respiration is more important than respiration by lungs.The moist,well vascularized skin places them in intimate contact with their environment.One might expect them to be vulnerable to changes in water or air quality resulting from diverse pollutants.Amphibians are thermal-conformers,thus making them sensitive to environmental temperature changes,which may be especially important for tropical montane(e.g.,cloud forest)species that have experienced little temperature variation.Such species may have little acclimation ability in rapidly changing thermal regimes.In general,amphibians have small geographic ranges,but this is accentuated in most terrestrial species(the majority of salamanders;a large proportion of frog specie also fit this category)that develop directly from terrestrial eggs that have no free-living larval stage.These small ranges make them especially vulnerable to habitat changes that might result from either direct or indirect human activities.Line510152025303540 Living amphibians(Class Amphibia,Subclass Lissamphibia)include frogs(5,600 currently recognized species),salamanders(570 species),and caecilians(175 species).Most information concerning declines and extinctions has come from studies of frogs,which are the most numerous and by far the most widely distributed of living amphibians.Salamanders facing extinctions are centered in Middle America.Caecilians are the least well known;little information on their status with respect to extinction exists.The Global Amphibian Assessment completed its first round of evaluating the status of all then-recognized species in 2004,finding 32.5%of the known species of amphibians to be“globally threatened”by using the established top three categories of threat of extinction(i.e.Vulnerable,Endangered,or Critically Endangered);43%of species have declining populations.In general,greater numbers as well as proportions of species are at risk in tropical countries.Updates from the Global Amphibian Assessment are ongoing and show that,although new species describes since 2004 are mostly too poorly known to be assessed,20%of analyzed species are in the top three categories of threat.Species from montane tropical regions,especially those associated with stream or streamside habitats,are most likely to be severely threatened.*A group of one or more populations of an organismor organisms seen by taxonomists to form a unit455055606570L2 P4天道教育 h t t p:/t i a n d a o e d u.co m/ScienceCONTINUE21The main idea of the first two paragraphs is that amphibiansA)have traditionally been very persistent but arenow disproportionately endangered.B)face a risk of extinction greater than that of anyother group of organisms.C)have been praised by scientists for their ability towithstand the last four mass extinctions.D)now face extinction across all species because ofhuman activity.23As used in line 10,”compelling”most nearly meansA)urgent.B)captivating.C)overwhelming.D)forced.The author implies that the study of frogs and other amphibians is especially important because these speciesA)are sensitive to environmental changes that mightaffect other species in the future.B)have less ability to adapt to changingenvironmental conditions than other species do.C)are exposed to more predators and parasites thanother species are.D)embody the principles of evolution more clearlyand linearly than other species do.4Which choice provides the best evidence for the answer to the previous question?A)lines 13-17(“Paradoxicallyhealth”)B)lines 17-20(“The typical environments”)C)lines 21-23(“Frog.parasites”)D)lines 23-25(“Amphibianslungs”)5The author discusses the thermal conformity of amphibians in order toA)show why they are so susceptible to being harmedby changes in their environments.B)contrast them with other types of animals thatother scientists have studied in greater depth.C)prove that amphibians are the most sensitive ofall animals and therefore need to be treated withgreater care.D)question why the geographic ranges ofamphibians is so small compares to that of otherspecies.6Frogs have been studied more than other amphibians becauseA)members of other species are less common andnot found in as many places.B)they model human biology better than otheramphibians.C)so many other amphibian species have recentlybecome extinct.D)their sensitivity to environment makes them idealfor study.L2 P4天道教育 h t t p:/t i a n d a o e d u.co m/CONTINUE3Science7Which choice provides the best evidence for the answer to the previous question?A)lines 43-46(“Livingspecies”)B)lines 46-50(“Mostamphibians”)C)lines 50-51(“SalamandersAmerica”)D)lines 51-53(“Caeciliansexists”)8The phrase“globally threatened”(line 57-58)primarily serves toA)show that scientists consider amphibians futureperilous by the seriousness of the terms.B)lend authority to the authors argument aboutamphibian extinction by using a well-recognizedphrase.C)quote the scientists at The Global AmphibianAssessment so that readers understand the limitednature of their statistics.D)demonstrate that,though amphibians have beenreferred to as threatened,this term is questionablyapplied.9The graph supports the statement in the last paragraph about the evaluation completed in 2004 byA)demonstrating that approximately 1/3 ofamphibian species are in the top three categoriesof threat.B)showing that only 1%of amphibians have goneextinct in the wild,despite predictions to thecontrary.C)highlighting that scientists have not collectedenough data on a significant number ofamphibian species.D)proving that the remaining species of amphibianswill become extinct in the future.10Information from the graph and the passage suggests that the second-largest category includes most of the worldsA)caecilians.B)salamanders.C)frogs.D)montane amphibians.11The third-largest category represents amphibians that are classified asA)endangered.B)least concern.C)extinct.D)vulnerable.E)*Im still a watermark.My creator isWechat:satxbs123.Look how nice and fresh I am!L2 P4天道教育 h t t p:/t i a n d a o e d u.co m/ScienceCONTINUE4Questions 1-11 are based on the following passage.Adapted from Abi Berger,”Magnetic Resonance Imaging,”2002 by Abi berger.Magnetic resonance imaging(MRI)uses the bodys natural magnetic properties to produce detailed images from any part of the body.For imaging purposes the hydrogen nucleus(a single proton)is used because of its abundance in water and fat.The hydrogen proton can be likened to the planet earth,spinning on its axis,with a north-south pole.In this respect it behaves like a small bar magnet.Under normal circumstances,these hydrogen proton“bar magnets”spin in the body with their axes randomly aligned.When the body is placed in a strong magnetic field,such as an MRI scanner,the protons axes all lined up.This uniform alignment creates a magnetic vector oriented along the axis of the MRI scanner.MRI scanners come in different field strengths,usually between 0.5 and 1.5 tesla.The strength of the magnetic field can be altered electronically from head to toe using a series of gradient electric coils,and,by alerting the local magnetic field by these small increments different slices of the body will resonate as different frequencies are applied.When the radiofrequency source is switched off the magnetic vector returns to its resting state,and this causes a signal(also a radio wave)to be emitted.It is this signal which is used to create the MR images.Receiver coils are used around the body part in question to act as aerials to improve the detection of the emitted signal.The intensity of the received signal is then plotted on a grey scale and cross sectional images are built up.Multiple transmitted radiofrequency pulses can be used in sequence to emphasis particular tissues or abnormalities.A different emphasis occurs because different tissues relax at different rates when the transmitted radiofrequency pulse is switched off.The time taken for the protons to fully relax is measured in two ways.The first is the time taken for the magnetic vector to return to its resting state and the second is the time needed for the axial spin to return to its resting state.The first is called T1 relaxation,the second is called T2 relaxation.An MR examination is thus made up of a series of pulse sequences.Different tissues(such as fat and water)have different relaxation times and can be identified separately.By using a“fat suppression”Line510152025303540pulse sequence,for example,the signal from fat will be removed,leaving only the signal from any abnormalities lying within it.Most diseases manifest themselves by an increase in water content,so MRI is a sensitive test for the detection of disease.The exact nature of the pathology can be more difficult to ascertain:for example,infection and tumor can in some cases look similar.A careful analysis of the images by a radiologist will often yield the correct answer.There are no known biological hazards of MRI because,unlike x ray and computed tomography,MRI uses radiation in the radiofrequency range which is found all around us and does not damage tissue as it passes through.*God help those who help themselves.We help thosewho trust us.Contact Wechat:satxbs123,help is waiting.Magnetic Vector(T1)and Axial Spin(T2)Relaxation Times for Different Molecules/Tissues,in Milliseconds Tissue T1(msec)T2(msec)Source:Data from Bottomley PA,et al.“A Review of Normal Tissue Hydrogen NMR Relaxation Times and Relaxation Mechanisms from 1-100 MHz:Dependence on Tissue Type,NMR Frequency,Temperature,Species,Exision,and age.”Med Phys 1984;11:425-448455055WaterGray MatterMuscleLiverFatTendon4,0009009005002504002,000905040705L2 P5天道教育 h t t p:/t i a n d a o e d u.co m/CONTINUE5Science4Over the course of the passage,the main focus shifts fromA)an explanation of how magnetic resonanceimaging(MRI)works to a discussion of MRIspractical advantages.B)a story about the origin of magnetic resonanceimaging(MRI)to a discussion of alternativeimaging methods used by scientists.C)an explanation of tissue relaxation rates to asummary of the magnetic properties of hydrogenprotons.D)an introduction about the properties ofradiofrequency waves to a criticism of the healthrisks of x-ray devices.5The“planet earth”image in line 6-7 mainly serves to A)highlight an unlikely parallel between the fields ofbiology and astronomy.B)inject a note of humor into an otherwise seriousexplanation of magnetic resonance imaging.C)create a pun centered on the idea that hydrogen isnecessary for life on this planet.D)communicate a complex scientific idea using amore familiar concept.6It can reasonably inferred from the passage that electromagnetic waves in the radio frequency rangeA)do not create long-lasting effects on the humanbody.B)only create magnetic fields in tissues with highwater content.C)are stronger than waves in the x-ray range.D)always travel in the same direction.1Which choice best reflects the authors point of view regarding magnetic resonance imaging(MRI)?A)It is the most important tool used by scientists toaid in the diagnosis of particular diseases.B)It is a valuable and effective technique but shouldbe used sparingly in order to prevent possibledamage to the body.C)It is a breakthrough technology that willrevolutionize the treatment of particular ailments.D)It is a useful tool in disease diagnosis,althoughspecialized training is required to accuratelyinterpret MRI images.23Which choice provides the best evidence for the answer to the precious question?A)lines 17-21(“The strength.applied”)B)lines 30-34(“Multiple.off”)C)lines 42-47(“Different.it”)D)lines 48-54(“Most.answer”)It can reasonably be inferred from the passage that,like a bar magnet,the nucleus of a hydrogen atomA)spins in a counter-clockwise direction.B)is responsive to external magnetism.C)attracts metallic substances.D)is surrounded by electrons.L2 P5天道教育 h t t p:/t i a n d a o e d u.co m/ScienceCONTINUE67Which choices provides the best evidence for the answer to the previous question?A)lines 22-24(“When.emitted”)B)lines 28-29(“The.up”)C)lines 34-39(“The time.state”)D)lines 55-59(“There.through”)8As used in line 49,sensitive most nearly meansA)appreciativeB)unstableC)discerningD)observant9The data in the table support the authors point thatA)pulse relaxation times can be used to identifydifferent tissues in the body.B)magnetic resonance imaging is safer than otherimaging techniques.C)infections and tumors look similar using magneticresonance imaging.D)hydrogen protons behave like a small bar magnet.10According to the table,which tissue is the first to return to its original magnetic vector resting state?A)Water/CSFB)LiverC)FatD)Tendon11It can reasonably be inferred from the table that A)some tissues display axial spin relaxation times aremuch longer than their magnetic vector relaxationtimes.B)it generally takes longer for the magnetic vector toreturn to its resting state than the axial spin.C)it often takes twice as long for the axial sp