7．Big trees are incredibly important ecologically．For a start，they provide food for countless other species and shelter for many animals．With their tall branches in the sun，they capture vast amounts of energy．This allows them to produce massive crops of fruit and flowers that sustain much of the animal life in the forest．
Only a small number of tree species have the genetic abilityto grow really big．The biggest are native to North America，but big trees grow all over the globe，from the tropics to the forests of the high latitudes（緯度）．To achieve giant size，a tree needs three things：the right place to establish its seedling，good growing conditions and lots of time with low adult death rate．Lose any of these，and you will lose your biggest trees．
In some parts of the world，populations of big trees are dwindling because their seedlings cannot survive．In southern India，for instance，an aggressive non-native bush，Lantana camara，is invading the floor of many forests．Lantana grows so thickly that young trees often fail to take root．With no young trees to replace them，it is only a matter of time before most of the big trees disappear．
Without the right growing conditions，trees cannot get really bigand there is some evidence to suggest tree growth could slow in a warmer world，particularly in environments that are already warm．Having worked for decades at La Selva Biological Station in Puerto Viejo de Sarapiqui，Costa Rica，David and Deborah Clark and colleagues have shown that tree growth there declines markedly in warmer years．"During the day，their growth shuts down when it gets too warm，and at night they consume more energy because theirmetabolic（新陳代謝的） rate increases，"explains David Clark．With less energy produced in warmer years and more being consumed just to survive，there is even less energy available for growth．
The Clarks'theory，if correct，means tropical forests would shrink over time．The largest，oldest trees would progressively die off and tend not to be replaced．According to the Clarks，this might cause a destabilization of the climate； as older trees die，forests would release some of their stored carbon into the atmosphere，causing a cycle of further warming，forest shrinkage and carbon emissions．
Besides，big trees face threats from elsewhere．

73．According to the passage，big trees make great contributions to theecosystem becauseC．
A．they can capture large amounts of energy
B．they determine the change of global climate
C．they provide the essentials for many creatures
D．they can avoid a new cycle of further warming
74．All the following factors are a must for making big treesEXCEPTD．
A．no deadly damage
B．genetic contribution
C．ideal environmentfor growth
D．high-latitude location
75．The word"dwindling"（paragraph3）is closest in meaning to"D"．
A．exploding
B．growing
C．changing
D．declining
76．What is the best title of the passageA？
A．Big trees in trouble．
B．Advantages of big trees．
C．Results of big trees'disappearing．
D．Importanceof big trees to humans．
77．What will the author most probably discuss after the last paragraphA？
A．More threats to the existence of big tress．
B．The effect of human activities on big trees．
C．Benefits of big trees to the whole atmosphere．
D．Comparison between common trees and big ones．

分析 本文屬于說明文閱讀，作者在文章中向我們講述了大樹成長的必要條件，但是如今由于無法完全達到這些條件，所以導(dǎo)致了大樹的數(shù)量越來越少，作者通過這篇文章呼吁我們要保護大樹．

解答 73．C  細節(jié)理解題．根據(jù)第一段"Big trees are incredibly important ecologically．For a start，they provide food for countless other species and shelter for many animals．"可知大樹為其他物種提供食物，并為很多動物提供庇護所，故選C．
74．D  細節(jié)理解題．根據(jù)第二段"To achieve giant size，a tree needs three things：the right place to establish its seedling，good growing conditions and lots of time with low adult death rate．"可知一棵樹生長需要沒有致命的傷害，理想的生長環(huán)境，以及良好的遺傳，只有D項在文中沒有被提到，故選D．
75．D  詞義猜測題．根據(jù)第三段In some parts of the world，populations of big trees are dwindling because their seedlings cannot survive．可知是因為幼苗無法存活，所以導(dǎo)致了大樹的數(shù)量下降，故選D．
76．A  標題判斷題，通讀全文可知作者在本文中提到了大樹成長的必要條件，但是由于這些條件無法完全達到，所以大樹的數(shù)量越來越少，故選A．
77．A  推理判斷題．根據(jù)最后一段"Besides，big trees face threats from elsewhere．"可知除此之外大樹還面臨著來自其他方面的威脅，所以下文最有可能講所大樹面臨的其他威脅．故選A．

點評 考查學(xué)生的細節(jié)理解和推理判斷能力．做細節(jié)理解題時一定要找到文章中的原句，和題干進行比較，再做出正確選擇．在做推理判斷題時不要以個人的主觀想象代替文章的事實，要根據(jù)文章事實進行合乎邏輯的推理判斷．

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"If it may sound like a lot for you，brisk walking （快走） is also a good exercise．And if you're bit of a couch potato，this is a good place to start．

61．From paragraph one，we could knowC．
A．the study took 10years
B．more than 1000joggers took part in the study
C．people with no exercise had the highest death rates
D．joggers and non-joggers are likely to die
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B．Jog at a pace of about 11km/h for 2.5hours in total in a week．
C．Jog at a pace of about 11km/h more than three times a week．
D．Jog at a pace of about 8km/h for 2.5hours a day．
63．The underlined word"strenuous"meansB．
A．light           
B．strong          
C．enough           
D．frequent
64．According to the passage，which of the following is Not True？B
A．There isn't an upper limit for safe exercise across the world now．
B．Running marathons helps keep your heart healthy．
C．Light and moderate jogging may help people live longer．
D．The moderate-intensity activity time in a week could be about 140minutes．
65．What is the main idea of the passage？D
A．Jogging everyday is good to health．
B．Brisk walking is better than jogging．
C．Jogging is not a good activity for people who suffer heart diseases．
D．Jogging too much is no better than doing no exercise．

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科目：高中英語 來源： 題型：閱讀理解

17．They already guide blind and disabled people； now dogs are to be trained to help people with dementia（癡呆） or Alzheimer's．Alzheimer's can make people confuse night and day or forget basic things such as washing or drinking enough water．
    The dogs will be trained to respond to sound triggers（觸發(fā)器） in the home that cause them to perform tasks．The duties will include reminding their owners to take medicine，as well as encouraging them to eat，drink and sleep regularly．
    The idea was developed by design students at the Glasgow School of Art and will now be put into practice by Alzheimer's Scotland and Dogs for the Disabled．The first dogs will be distributed to four Scottish couples，where one of the partners is in the early stages of dementia．Some 670，000 people in Britain have dementia and one in three over 65s will develop the condition．By 2021 this is expected to rise to one million．
    Joyce Gray of Alzheimer's Scotland said，"People in the early stages of dementia are still able to live a relatively normal life，and dogs help to maintain routine．"Another advantage of using the pets as companions is that dogs can give them a sense of silent support and companionship．Ms Gray said，"The evidence is that people may forget familiar faces but not pets．It's such a strong bond that people often remember them longest．People don't need to communicate verbally （言語地） but they can still interact．You can have a speechless bond．"
    Helen McCain，director of Dogs for the Disabled，said，"People with dementia often forget to take the medicine．If a dog presents them with a bag with pills in it there's a greater chance of them taking it．The dog would also encourage the owner to take them out for walks，ensuring they keep exercising and interacting with other people．"
32．In Britain people with dementiaA
A．a(chǎn)re likely to increase in number    
B．a(chǎn)re mostly over 65 years old
C．will be trained to respond to sound triggers    
D．will be able to live a relatively normal life
33．The dogs are taught to perform tasks byD．
A．making some sound signals  
B．communicating with the patients
C．reminding the patients by barking   
D．reacting to some sound triggers
34．What does the underlined word"them"in Paragraph 4 refer to？C   
A．Faces．          B．Triggers．      C．Pets．           D．Companions．
35．What is mainly talked about in the passage？B
A．The idea of dementia dogs was developed by students．
B．Dogs are trained to assist Alzheimer's patients．
C．British people with Alzheimer's are in poor condition．
D．The dementia dogs perform most duties of a doctor．

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