Many species of animals which once lived on the earth are no longer _________. A. in practiceB. in existenceC. in commonD. in turn
Many species of animals which once lived on the earth are no longer _________.
A. in practice
B. in existence
C. in common
D. in turn
相关考题：
Which of the following is the result of the volcanic eruption?A. People stop traveling in EuropeB. Airlines suffer from the loss of planesC. It becomes dangerous for animals to eat outsideD. Farmers have lost many of their animals
The Timber rattlesnake is now on the endangered species list, and is extinct in two eastern states in which it once _______ .A thrived B swelled C prospered D flourished
"Hidden" Species May Be Surprisingly CommonCryptic species animals that appear identical but are genetically quite distant—may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution.Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat, in Frankfurt, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographieal regions.Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions. "Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered. " Says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. "It could be as high as 30%. " Pfenninger says."I'm extremely surprised by their results. " Says Alex Smith of the University of Guelph in Ontario, Canada. "It's a call to arms to keep doing the broad kind of genetic studies that we are doing. "Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will be able to decide how many cryptic species exist throughout the animal kingdom.Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU).The reclassifications are more than an academic exercise. They define populations that have evolved independently of each other and whose genetic differences can have significant consequences. In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe. Ultimately, what was thought to be a single species was actually made up of six sibling species, only three of which transmitted the disease. "The basic unit in biology is always the species, and you have to know what you are dealing with. " Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studied.Which of the following about the significance of the research on cryptic species is NOT true?A．The results of the research can help the development of many other research areas.B．The results of the research can help the development of biodiversity estimates.C．The results of the research can help our understanding of infectious disease evolution.D．The results of the research can help our understanding of "survival of the fittest. "
Which of the following is the result of the volcanic eruption?A．People stop traveling in EuropeB．Airlines suffer from the loss of planesC．It becomes dangerous for animals to eat outsideD．Parmers have lost many of their animals
Modern zoos are very different from zoos that were built fifty years ago.At that time, zoos were places (1) people could go to see animals from many parts of the world.They animals lived in cages that were made (2) Concrete with iron bars, cages that were easy to keep clean.Unfortunately for the animals, the cages were small and impossible to hide in.the zoos environment was anything (3) natural.Al though the zoo keepers took good care of the animals and fed them well, many of the animals did not thrive: they behaved in strange ways, and they often became illIn modern zoos, people can see animals in more natural habitats.The animals are(4)more freedom in large areas so that they can live more comfortably as they would in nature Even the appearance of zoos has changed, trees and grass grow in the cages, and streams of water flow (5) the areas that animals live in.(完型填空)A.OfB.ButC.WhereD.OverE.Given
We now know that about ____ of all the kinds of seaweed are animals.A: one fourB: once fourC: once fourthD: one fourth
The loss of biological diversity has become most spectacularly noticeable in extinction or decline of populations of large and well-known animals.Many animal species have become extinct since the 1700’s, among them the California grizzly bear, the dodo, and the passenger pigeon.Hundreds of other animal species are threatened.In North America, endangered species include the black-footed ferret, the California condor, the desert tortoise, and the whooping crane.Most species in danger of extinction anywhere in the world are suffering from the intrusion (侵入) of human beings.The Asian elephant, for example, has become an endangered species due to the expansion of the human population throughout its range in southern Asia.In Africa, the African elephants are being killed off for their tusks.Monkeys and other primates throughout the world are threatened by hunting, capture for medical use, and the destruction of their habitats.And the rhinoceroses, lions, and other large mammals of the African savanna (grassy plains with scattered trees) compete for land and life with some of the most rapidly growing human populations in the world.The loss of biological diversity is most severe, however, in the tropical rain forests.The forests of the tropics are particularly vulnerable to disturbance because the soils have a low capacity for retaining nutrients.Most of the forests’ nutrient elements are held in the tissues of plants.When loggers and farmers destroy existing plant cover, the nutrients are washed from the land into streams, and the land itself becomes less able to support life.Destruction of these forests destroys the habitat of hundreds, sometimes thousands, of species from such creatures as the howler monkey and indigo macaw, to less visible species of plants, insects, and microbes, many of which are not yet known to science.1.The author points out that species extinction ().A.is most noticeable in North AmericaB.is mainly taking place among large animalsC.quickened with industrialization of the societyD.never took place before the 1700’s2.Which of the following is NOT mentioned with regard to human intrusion?A.Elephants are killed off for their tusksB.Some primates are hunted for medical useC.Growing human population results in the competition for land and life among animalsD.Men live increasingly on animals as their source of food.3.The chief cause of the gradual disappearance of biological diversity is ().A.human crueltyB.human interferenceC.the increase of human populationD.the disappearance of the forests4.In tropical forests，().A.animals live a hard life due to competitionB.a lot of species die out for lack of foodC.rains constitute the major threat to speciesD.a greater number of animals are yet to be known5.It can be inferred that species extinction ().A.proceeds of a faster rate than noticeableB.is the worst among well-known animalsC.is the most severe in AfricaD.is chiefly due to competition among species
翻译句子Several years passed on Earth, which were only a few days in heaven. Niu Lang and Zhi Nv lived happily together and had two children before the Queen of Heaven discovered Zhi Nv's absence.
Many students start each term with an award check, but by the time books are bought, food is paid for, and a bit of social life ＿＿, it looks rather emaciated. A. lives B. lived C. was lived D. has lived
共用题干第二篇The Book of LifeSo far,scientists have named about 1.8 million living species,and that's just a fraction of what proba- bly exists on Earth.With so many plants,animals,and other creatures covering the planet,it can be toughto figure out what type of spider is moving up your leg or what kind of bird is flying by.A soon-to-be-launched Web site might help. An international team of researchers has announced thecreation of a Web-based Encyclopedia of Life(EoL).The project aims to catalog every species on Earth in asingle,easy-to-use reference guide.To get the encyclopedia started,the creators will use information from scientific databases that alreadyexist.And eventually,in special sections of the site,nonscientists with specialized knowledge will get to join in.Bird-watchers,for example,will be able to input which birds they've seen and where.The technologyfor this kind of tool has only recently become available.As the EoL develops, you might find it useful for school projects.The site will feature special pages forkids who are studying ecosystems（生态系统）in their neighborhoods. To make sure the encyclopedia isaccurate,scientists will review much of the information added to it. People who visit the site will be able tochoose to leave out pages that haven't been reviewed.Another convenient feature of the EoL is that you'll be able to pick the level of detail you see to matchyour interests,age,and current knowledge.If you wanted to learn about bears for a science class report,forexample,you could use the"novice"setting to get basic information about the animals.On the"expert" setting,on the other hand,you could get much more detailed information about the history,literature and exploration of bears.It now takes years for scientists to collect all the data they need to describe and analyze species.Thecreators of the Encyclopedia of Life hope that their new tool will speed that process."Spider" and"bird"mentioned in Paragraph 1 are examples to illustrate_______________.A:animals are people's friendsB:there are numerous living species on EarthC:it is easy to see spiders and birdsD:there are many types of spiders and birds
共用题干第三篇Longer Lives for Wild ElephantsMost people think of zoos as safe places for animals,where struggles such as having difficulty finding food and avoiding predators（猛兽）don't exist. Without such problems,animals in zoos should live to a ripe （成熟的）old age.But that may not be true for the largest land animals on Earth.Scientists have known that elephants in zoos often suffer from poor health.Sometimes,they even become unable to have babies.To learn more about how captivity（圈养）affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands. Zoos keep detailed records of all the animals in their care,documenting factors such as birth dates,illnes-ses,weight and death.These records made it possible for the researchers to analyze 40 years of data on 800 African and Asian elephants in zoos across Europe.The scientists compared the life spans of the zoo-born fe-male elephants with the life spans of thousands of wild female elephants in Africa and Asian elephants that work in logging camps（伐木场）, over approximately the same time period.The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild counterparts who died of natural causes lived an average of 56 years一more than three times as long. Female Asian elephants followed a similar pattern. In zoos,they lived 18.9 years,while those in the logging camps lived 41.7 years.Scientists don't know yet why wild elephants seem to get on so much better than their zoo-raised coun-terparts.Georgia Mason,a biologist at the University of Guelph in Canada who led the study,thinks stress and obesity（肥胖症）may be to blame. Zoo elephants don't get the same kind of exercise they would in the wild,and most are very fat. Social lives of elephants are also much different in zoos than in the wild,where they live in large herds and family groups.The study raises some questions about acquiring more elephants to keep in zoos.While some threatened and endangered species living in zoos reproduce（生殖）successfully and maintain healthy populations,that doesn't appear to be the case with elephants.Unlike other animals in zoos,zoo-raised elephantsA:live a long lifeB:give birth to many babiesC:develop poor healthD:have difficulty getting food
共用题干第三篇Longer Lives for Wild ElephantsMost people think of zoos as safe places for animals,where struggles such as having difficulty finding food and avoiding predators（猛兽）don't exist. Without such problems,animals in zoos should live to a ripe （成熟的）old age.But that may not be true for the largest land animals on Earth.Scientists have known that elephants in zoos often suffer from poor health.Sometimes,they even become unable to have babies.To learn more about how captivity（圈养）affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands. Zoos keep detailed records of all the animals in their care,documenting factors such as birth dates,illnes-ses,weight and death.These records made it possible for the researchers to analyze 40 years of data on 800 African and Asian elephants in zoos across Europe.The scientists compared the life spans of the zoo-born fe-male elephants with the life spans of thousands of wild female elephants in Africa and Asian elephants that work in logging camps（伐木场）, over approximately the same time period.The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild counterparts who died of natural causes lived an average of 56 years一more than three times as long. Female Asian elephants followed a similar pattern. In zoos,they lived 18.9 years,while those in the logging camps lived 41.7 years.Scientists don't know yet why wild elephants seem to get on so much better than their zoo-raised coun-terparts.Georgia Mason,a biologist at the University of Guelph in Canada who led the study,thinks stress and obesity（肥胖症）may be to blame. Zoo elephants don't get the same kind of exercise they would in the wild,and most are very fat. Social lives of elephants are also much different in zoos than in the wild,where they live in large herds and family groups.The study raises some questions about acquiring more elephants to keep in zoos.While some threatened and endangered species living in zoos reproduce（生殖）successfully and maintain healthy populations,that doesn't appear to be the case with elephants.It can be inferred from the last paragraph that______________.A:zoo-born elephants should be looked after more carefullyB:zoos should keep more animals except elephantsC:it may not be wise to keep elephants in zoosD:elephants are no longer an endangered species
共用题干第二篇Human and the EarthIn terms of the evolution of life on Earth,human beings have just arrived.Despite their shori time on Earth,however,people have brought about enormous changes to the surface of the planet一changes far out of proportion to the interval of time they have occupied it.People have more control over their surroundings than any other species on Earth.With the combination of intelligence and manual skill(allowing us to make and use tools),people have found ways to use plant and animal resources,mineral ores,fuels,and many other materials and resources from the Earth.As the number of people on Earth increases,it becomes increasingly difficult for the population to survive on the resources of the land.The amount of land is limited.Although agricultural production can be increased by use of machinery such as tractors and the addition of fertilizer,the land ultimately can produce only so much food and no more.As the human population grows,people consume more.Clearly,some locations on Earth already have too many people;in many of these areas,future increases will surely bring about more poverty and suffering. Yet people in rich nations use proportionally far more of the available resources than people in poorer nations.As they consume these resources without restraint,they also waste large amounts of them.People are only a very small fraction of all the living things on the planet.Yet their numbers create a drain on resources that can't be renewed.For example,the amount of water on Earth is limited,this water is cleaned through natural processes.However,the natural processes for filtering water can clean only a certain amount of water by removing the pollution.Likewise,a limited amount of petroleum can be found under the Earth's surface.Petroleum is a valuable resource.Should people use it up to manufacture petrol for automobiles?As people work to control the planet and make life comfortable,are they using up resources that are needed for their survival?Why have people more control over their surroundings than any other species on Earth?A:Because of their intelligence and manual skill.B:Because they can use plant and animal resources,mineral ores and fuels.C:Because they are cleverer than any other animals on Earth.D:Both A and B.
共用题干第二篇The Book of LifeSo far, scientists have named about 1.8 million living species（物种）,and that's just a small part of what probably exists on Earth.With so many plants,animals,and other creatures covering the planet,it can be tough to figure out what type of spider is moving up your leg or what kind of bird is flying by.A soon-to-be-launched Web site mighit help. An international team of researchers has announced the creation of a Web-based Encyclopedia（百科全书）of Life(EoL).The project aims to catalog every species on Earth in a single,easy-to-use referenice guide.To get the encyclopedia started,the creators will use information from scientific databases（数据库）that already exist. And eventually , in special sections of the site , nonscientists with specialized（专门的） knowledge will get to join in Bird-watchers,for example,will be able to input which birds they'ye seen and where.The technology for this kind of tool has only recently become available.As the EoL develops,you might find it useful for school projects.The site will feature special pages for kids who are studying ecosystems（生态系统）in their neighborhoods. To make sure the encyclopedia is accurate,scientists will review much of the information added to it.People who visit the site will be able tochoose to leave out pages that haven't been reviewed.Another convenient feature of the EoL is that you'11 be able to pick the level of detail you see to match your interests,age,and current knowledge.If you wanted to learn about bears for a science class report,for example,you could use the"novice"setting to get basic information about the animals.On the"expert" setting,on the other hand,you could get much more detailed information about the history,literature,andexploration of bears.It now takes years for scientists to collect all the data they need to describe and analyze species.The creators of the Encyclopedia of Life hope that their new tool will speed that process.The goal of the creation of the EoL is to________.A:collect enough data to analyze the living species on EarthB:enlarge an existing Web site of the living species on EarthC:work out an easy-to-use catalog of every living species on EarthD:add new information to the existing databases of the living species on Earth
共用题干第二篇The Book of LifeSo far, scientists have named about 1.8 million living species（物种）,and that's just a small part of what probably exists on Earth.With so many plants,animals,and other creatures covering the planet,it can be tough to figure out what type of spider is moving up your leg or what kind of bird is flying by.A soon-to-be-launched Web site mighit help. An international team of researchers has announced the creation of a Web-based Encyclopedia（百科全书）of Life(EoL).The project aims to catalog every species on Earth in a single,easy-to-use referenice guide.To get the encyclopedia started,the creators will use information from scientific databases（数据库）that already exist. And eventually , in special sections of the site , nonscientists with specialized（专门的） knowledge will get to join in Bird-watchers,for example,will be able to input which birds they'ye seen and where.The technology for this kind of tool has only recently become available.As the EoL develops,you might find it useful for school projects.The site will feature special pages for kids who are studying ecosystems（生态系统）in their neighborhoods. To make sure the encyclopedia is accurate,scientists will review much of the information added to it.People who visit the site will be able tochoose to leave out pages that haven't been reviewed.Another convenient feature of the EoL is that you'11 be able to pick the level of detail you see to match your interests,age,and current knowledge.If you wanted to learn about bears for a science class report,for example,you could use the"novice"setting to get basic information about the animals.On the"expert" setting,on the other hand,you could get much more detailed information about the history,literature,andexploration of bears.It now takes years for scientists to collect all the data they need to describe and analyze species.The creators of the Encyclopedia of Life hope that their new tool will speed that process."Spider" and "bird" mentioned in Paragraph 1 are examples to illustrate________.A:animals are people’s friendsB:there are numerous living species on EarthC:it is easy to see spiders and birdsD:there are many types of spiders and birds
单选题Why do some people get sick after drinking the water from the river?ABecause the river is pollutedBBecause the river makes the earth more beautifulCBecause the river can only offer water to animalsDBecause there are too many animals and plants in the river
单选题According to the experts, the reversal of the Earth’s magnetic field would _____.Adestroy almost all the creatures on the EarthBcause some species extinctions on the EarthCnot be as disastrous as the previous oneDcause no big trouble for man and animals
单选题Some people argue that it would do more harm than good for plants and animals to develop through artificial selection. Which statement best supports this argument?ARoses no longer smell like roses.BPurebred dogs are disappearing.CHumans are harmful agents of plant and animal evolution.DMany domesticated plants and animals can no longer survive in the wild.
单选题The relationship of jati to varna is most comparable to which of the following relationships?AThe relationship of individual playing cards to a 52-card deckBThe relationship of a group of related species of animals to the genus to which the species belongCThe relationship of a compact disk to the songs contained on that diskDThe relationship of a transmission to the car in which the transmission has been installedEThe relationship of an updated version of software to the original version of that software
单选题The problem with Elkhorn and stag horn corals lies in that _____.Athey were not much-liked by many peopleBthey were not well-known enough to be an iconCthey were not considered animals by many peopleDthey were not added to the list of Endangered Species
单选题During the transition of the Earth’s magnetic field _____.Athe compass will become uselessBman and animals will be confused as to directionsCthe magnetic strength of the Earth will disappearDthe magnetic strength of the Earth will be stronger
问答题Practice 2 Transgenic plants and animals result from genetic engineering experiments in which genetic material is moved from one organism to another, so that the latter will exhibit a characteristic. Business corporations, scientists, and farmers hope that transgenic techniques will allow more cost-effective and precise plants and animals with desirable characteristics that are not available using up to date breeding technology. Transgenic techniques allow genetic material to be transferred between completely unrelated organisms. In order for a transgenic technique to work, the genetic engineer must first construct a transgene, which is the gene to be introduced plus a control sequence. When making a transgene, scientists usually substitute the original promoter sequence with one that will be active in the correct tissues of the recipient plant or animal. The creation of transgenic animals is one of the most dramatic advances derived from recombinant DNA technology. A transgenic animal results from insertion of a foreign gene into an embryo. The foreign gene becomes a permanent part of the host animals’ genetic material. As the embryo develops, the foreign gene may be present in many cells of the body, including the germ cells of the testis or the ovary. If the transgenic animal is fertile, the inserted foreign gene (transgene) will be inherited by future progeny. Thus, a transgenic animal, once created, can persist into future generations. Transgenic animals are different from animals in which foreign cells or foreign organs have been engrafted. The progeny of engrafted animals do not inherit the experimental change. The progeny of transgenic animals do. The techniques for creating a transgenic animal include the following: 1) picking a foreign gene, 2) placing the foreign gene in a suitable form called a “construct” which guides the insertion of the foreign gene into the animal genome and encourages its expression, and 3) injecting the construct into a single fertilized egg or at the very early embryo stage of the host animal. Much genetic engineering goes into the choice of a foreign gene and building a construct. The construct must have promoters to turn on foreign gene expression at its new site within the host animal genome. By choosing a particular promoter and splicing it in front of the foreign gene, we can encourage expression of our transgene within a specific tissue. One of the most important applications of transgenic animals is the development of new animal models of human disease. Transgenic animals can serve as models for many malignant tumors. Mice have been the most frequent hosts for transgenic modification, other domestic animals have also been used. One idea has been to create transgenic cows which secrete important pharmaceutical substances in their milk. Other attempts are being made to express human interferon in the milk of sheep. A transgenic crop plant contains a gene or genes which have been artificially inserted instead of the plant acquiring them through pollination. The inserted gene sequence (known as the transgene) may come from another unrelated plant, or from a completely different species: transgenic BT corn, for example, which produces its own insecticide, containing a gene from a bacterium. Plants containing transgenes are often called genetically modified or GM crops although in reality all crops have been genetically modified from their original wild state by domestication, selection and controlled breeding over long periods of time.
单选题Which of the italicized parts functions as an attribute（定语）?AThis is where Luxun once lived.BI don’t know where Luxun once lived.CWe haven’t yet settled the question where we are going to spend our summer vacation.DShe is going to live in Macao, where she has some close friends.