第2部分 阅读判断

Lackof Oxygen Delayed the Rise of Animals on Earth

Scientistshave long speculated as to why animal species didn’t flourish sooner, oncesufficient oxygen covered the Earth’s surface. Animals began to prosper at theend of the Proterozoic period, about 800 million years ago — but what about thebillion-year stretch before that, when most researchers think there also wasplenty of oxygen?

Well,it seems the air wasn’t so great then, after all.

Ina study published Oct. 31 in Science, Yale researcher Noah Planavsky and hiscolleagues found that oxygen levels during the “boring billion” period wereonly 0.1% of what they are today. In other words, Earth’s atmosphere couldn’thave supported a diversity of creatures, no matter what genetic advancementswere poised to occur.

“There is no questionthat genetic and ecological innovation must ultimately be behind the rise ofanimals, but it is equally unavoidable that animals need a certain level ofoxygen,” said Planavsky, co-lead author of the research along with ChristopherReinhard of the Georgia Institute of Technology. “We’re providing the firstevidence that oxygen levels were low enough during this period to potentiallyprevent the rise of animals.”

Thescientists found their evidence by analyzing chromium (Cr) isotopes in ancientsediments from China, Australia, Canada, and the United States. Chromium isfound in the Earth’s continental crust, and chromium oxidation is directlylinked to the presence of free oxygen in the atmosphere.

Specifically,the team studied samples deposited in shallow, iron-rich ocean areas, near theshore. They compared their data with other samples taken from younger localesknown to have higher levels of oxygen.

Oxygen’srole in controlling the first appearance of animals has long vexed scientists.“We were missing the right approach until now,” Planavsky said. “Chromium gaveus the proxy.” Previous estimates put the oxygen level at 40% of today’sconditions during pre-animal times, leaving open the possibility that oxygenwas already plentiful enough to support animal life.

Inthe new study, the researchers acknowledged that oxygen levels were “highlydynamic” in the early atmosphere, with the potential for occasional spikes.However, they said, “It seems clear that there is a first-order difference inthe nature of Earth surface Cr cycling” before and after the rise of animals.

“If we are right, ourresults will really change how people view the origins of animals and othercomplex life, and their relationships to the co-evolving environment,” saidco-author Tim Lyons of the University of California-Riverside. “This could be agame changer.”

Fundingsources for the research included the NASA Exobiology Program and the NationalScience Foundation’s Earth-Life Transitions program, awarded to Planavsky,Reinhard, and Lyons.

Theother members of the research team included Xiangli Wang, a postdoctoral fellowat Yale; Thomas Johnson, of the University of Illinois; Danielle Thomson, ofCarleton University; Peter McGoldrick, of the University of Tasmania; andWoodward Fischer, of the California Institute of Technology.

16.The study discovered the rise of animals occurred earlier than the Proterozoicperiod.

A.Right B. Wrong C. Not mentioned

17.Many researchers believe the oxygen level was high during pre-animal times.

A. Right B. Wrong C.Not mentioned

18. The teamwas funded by several research institutes.

A.Right B. Wrong C. Not mentioned

19. Geneticadvancements triggered the rise of animals.

A.Right B. Wrong C. Not mentioned

20. Thesamples studied in the research were collected in ocean areas.

A. Right B. Wrong C.Not mentioned

21. Thestudy revealed that chromium found in Earth’s continental crust remained stablebefore and after the rise of animals.

A.Right B. Wrong C. Not mentioned

22. TimLyons liked to play computer games in his spare time.

A.Right B. Wrong C. Not mentioned

参考答案：BACBABC

第3部分 概括大意与完成句子

FirstImage-recognition Software

1.Dartmouth researchers and their colleagues have created an artificial 1 ,software that uses photos to locate documents on the Internet with far gre jthan ever before.

2.The new system, which was tested on photos and is now being applied to , Ishows for the first time that a machine learning algorithm (运算法则)or ,ma9e I recognition and retrieva l is accurate and efficient enough toimprove large seaie , document searches online. The system uses pixel (像素)data in images and potentia y video — rather than just text — to locatedocuments. It learns to recognize the pixels associated with a search phrase bystudying the results from text-based image search engines. The knowledgegleaned (收集) from those results can then beapplied to other photos without tags or captions making for more accuratedocument search results.

3."Over the last 30 years," says Associate Professor Lorenzo Torresani,a co-author of the study, "the Web has evolved from a small collection ofmostly text documents to a modern, massive, fast-growing multimedia dataset,where nearly every page includes multiple pictures or videos. When a personlooks at a Web page, he immediately gets the gist (主旨)of it by looking at the pictures in it. Yet, surprisingly, all existing popularsearch engines, such as Google or Bing, strip away the information contained inthe photos and use exclusively the text of Web pages to perform the documentretrieva l. Our study is the first to show that modern machine vision systemsare accurate and efficient enough to make effective use of the informationcontained in image pixels to improve document search."

4.The researchers designed and tested a machine vision system — a type ofartificial intelligence that allows computers to learn without being explicitlyprogrammed — that extracts semantic (语义的) information from thepixels of photos in Web pages. This information is used to enrich thedescription of the HTML page used by search engines for document retrieva l. Theresearchers tested their approach using more than 600 search queries (查询)on a database of 50 million Web pages. They selected the text-retheva l searchengine with the best performance and modified it to make use of the additionalsemantic information extracted by their method from the pictures of the Webpages. They found that this produced a 30 percent improvement in precision overthe original search engine purely based on text.

23. Paragraph 1 __B__

24. Paragraph 2 __C__

25. Paragraph 3 __E__

26. Paragraph 4 __D__

A.Popularity of the new system

B.Publication of the new discovery

C.Function of the new system

D.Artificial intelligence software created

E.Problems of the existing search engines

F.Improvement in document retrieva l

27. The new system does documentretrieva l by __C__.

28. The new system is expected toimprove precision in __B__.

29. When performing documentretrieva l the existing search engines ignore __A__

30. The new system was found moreeffective in document search than the __E__

A.information in images

B.current popular search engines

C.using photos

D.machine vision systems

E.document search

F.description of the HTML page

He who has never hoped can never despair. 从来没有抱过什么希望的人也永远不会失望.
Blind men can judge no colours. 盲者不辨色。