4008-125-888
新航道秋季班
首页>托福考试备考专区>TPO阅读>托福TPO61阅读Passage 3完整原文

托福TPO61阅读Passage 3完整原文

2021-01-28 16:13来源:互联网作者:上海管理员

摘要:托福TPO试题基本所有参加托福考生必做试题,为更好服务于广大考生,上海新航道小编会及时的更新托福TPO试题信息,包括TPO试题、答案及解析等内容。在下文中小编整理了托福TPO61阅读Passage 3完整原文,希望对大家有所帮助,如在学习过程中有问题,可以加新航道上海学校专业老师微信(微信号shnc_2018)进行咨询。

托福TPO试题基本所有参加托福考生必做试题,在下文中上海新航道托福培训小编整理了托福TPO61阅读Passage 1完整原文,希望对大家有所帮助!


托福TPO61阅读Passage 3完整原文

Grasses of the Prairie

【Paragraph 1】 Around 140 species of grasses naturally occur in the arid Great Plains grasslands of North America One key to the prairie grasses' success is their ability to conserve water in a dry environment. Like most plants, grasses take in water through their roots and lose it as water vapor through tiny mouth-shaped valves, or stomata, in their leaves. The larger the surface of the leaf and the more stomata it bears, the greater the risk that the plant will lose too much moisture through evaporation and collapse Grasses are protected from this trauma by having a reduced number of stomata and by the design of their leaves, which take the form of narrow blades What' s more, the surfaces of these reduced leaves are often modified—corrugated with ridges or covered in hairs-so that the wind can' t sweep across the surface and draw out moisture The roughened surface holds a thin layer of humid air next to the leaf and thus helps to reduce the "evaporative demand," or drying power, of the atmosphere. Some grasses, including western wheatgrass, June grass, and blue grama, roil up the edges of their leaves during times of drought to help keep their tissues from drying out.

【Paragraph 2】 Why aren' t the stomata kept tightly closed to seal moisture inside the leaf? The reason is that the stomata also supply plants with fresh air for photosynthesis. If plants sealed their stomata, this life-sustaining process would come to a halt for lack of carbon dioxide. But if the stomata are thrown wide open, the plants risk death due to the loss of moisture through their gaping valves. Prairie grasses resolve this dilemma by strategic scheduling. In the fierce blaze of the midday sun, the stomata close so that water vapor is held in and carbon dioxide is kept out. In this state, the leaf can capture solar energy and store it in energy-rich molecules (a process that requires sunlight but not carbon dioxide). Then, in the cool of the evening, when the evaporative demand drops off, the stomata snap open, letting water vapor trickle out but also permitting carbon dioxide to flood into the leaf by mobilizing the energy that was stockpiled earlier in the day, the leaf uses this carbon dioxide to manufacture the sugars and other molecules that it needs for growth (a process that can be accomplished in total darkness). The result is that prairie grasses are partially nocturnal: they do most of their growing at night or in the early hours of the morning.

【Paragraph 3】 Prairie grasses also have another ingenious way of evading the demands of the sun. Like many grassland creatures (prairie dogs, ground squirrels, cottontails, badgers, and so on), they take refuge underground What we think of as “grass”-the aboveground leaves and stems-actually constitutes less than half of the organism Between 60 and 80 percent of the plant, by weight, typically grows below ground. A 3-meter stand of big bluestem is anchored underground by a mass of coarse, fibrous roots that reaches as much as 3 6 meters into the earth Blue grama, for its part, seldom lifts its seed heads very far above the ground, but its network of fine, branching roots can sometimes probe the soil for water almost two meters down.

【Paragraph 4】 These extensive systems of roots push thirstily through the soil, intent on sucking up every available drop of water. But if the soil is very dry, as it is during periods of drought, the roots can' t draw in enough moisture to keep pace with losses from the stomata. Grasses respond by transferring their most valuable resources (including sugars and proteins) from their leaves into their roots and, especially, into their rhizomes (underground stems). Dead to the world above ground-withered and crisp-the plants live frugally below the surface, drawing on their cached supplies and biding their time until the weather improves When the rains eventually return, as they inevitably do, the grasses explode into action, sending out fresh rhizomes, which in turn put out fresh leaves and roots, to produce a burgeoning network of tender growth. The amazingly resilient blue grama can revive from dormancy, become green, and grow on as little as five millimeters of rainfall.索取“原文+题目+答案+解析+MP3音频”,请加新航道上海老师微信(shnc_2018)

tf-1.jpg



相关热点: 托福tpo61

免费领取资料

免费领取最新剑桥雅思、TPO、SAT真题、百人留学备考群,名师答疑,助教监督,分享最新资讯,领取独家资料。

方法1:扫码添加新航道老师

微信号:shnc_2018

方法2:留下表单信息,老师会及时与您联系

热门课程

  • 走读班(6-10人)
  • 走读班(20-30人)
  • 住宿班(6-10人)
  • 住宿班(20-30人)
  • 托福一对一
课程名称 班级人数 课时 学费 报名
托福基础走读班(6-10人) 6-10人 144课时 ¥29800 在线咨询
托福全程走读班(6-10人) 6-10人 192课时 ¥39800 在线咨询
托福强化走读班(6-10人) 6-10人 96课时 ¥24800 在线咨询
托福十一特训班 6-10人 56 ¥15800 在线咨询
托福特训班(4周,走读) 8-10人 192 ¥34800 在线咨询
课程名称 班级人数 课时 学费 报名
托福全程班(20-30人,走读) 20-30人 192课时 ¥13800 在线咨询
托福强化班(20-30人,走读) 20-30人 96课时 ¥7800 在线咨询
托福冲刺班(20-30人,走读) 20-30人 96课时 ¥8800 在线咨询
课程名称 班级人数 课时 学费 报名
托福基础班(6-10人,住宿) 6-10人 144课时 ¥28800 在线咨询
托福全程班(4周,住宿) 6-10人 304课时 ¥41800 在线咨询
托福长线班(6-10人,住宿) 6-10人 380课时 ¥46800 在线咨询
托福词汇语法住宿班(6-10人) 6-10人 48课时 ¥8800 在线咨询
托福精听精读住宿班(6-10人) 6-10人 48课时 ¥8800 在线咨询
课程名称 班级人数 课时 学费 报名
托福全程班(20-30人,住宿) 20-30人 192课时 ¥15800 在线咨询
托福强化班(20-30人,住宿) 20-30人 96课时 ¥8800 在线咨询
托福冲刺班(20-30人,住宿) 20-30人 96课时 ¥9800 在线咨询
课程名称 班级人数 课时 学费 报名
托福一对一 1 按需定制 ¥980元 在线咨询
托福精听精读十一特训班 在线咨询
托福免费试听课 ¥0元 在线咨询

免责声明
1、如转载本网原创文章,请表明出处;
2、本网转载媒体稿件旨在传播更多有益信息,并不代表同意该观点,本网不承担稿件侵权行为的连带责任;
3、如本网转载稿、资料分享涉及版权等问题,请作者见稿后速与新航道联系(电话:021-64380066),我们会第一时间删除。

  • 徐家汇校区
  • 人民广场校区
  • 浦东校区
  • 中山公园校区
  • 杨浦校区
  • 闵行校区
  • 松江校区
  • 封闭集训营
  • 地址:徐汇区裕德路126号

    乘车路线:地铁1、4号线上海体育馆、3号线9号线宜山路站、11号线上海游泳馆站

  • 地址:南京西路338号天安中心24楼

    乘车路线:地铁1、2、8号线人民广场站

  • 地址:浦东新区世纪大道1128号耀通科技大厦3楼(地铁2号线世纪大道站12号口出)

    乘车路线:地铁2、4、6号线世纪大道站

  • 地址:长宁路1158号 贝多芬广场 A座4楼414室

    乘车路线:乘车路线:地铁3、4号线中山公园站

  • 地址:杨浦区国宾路18号万达广场A座18楼

    乘车路线:地铁10号线五角场站

  • 地址:东川路1779-19号

    乘车路线:地铁5号线 东川路站4号口出

  • 地址:松江大学城四期校区:文汇路928弄想飞天地2204

    乘车路线:地铁9号线松江大学城站下

  • 地址:上海市浦东新区惠南镇拱极路2151号

    乘车路线:地铁16号线惠南站

总部地址:北京市海淀区中关村大街28-1号6层601 集团客服电话:400-097-9266 总部:北京新航道教育文化发展有限责任公司

Copyright © www.xhd.cn All Rights Reserved 京ICP备05069206

  • 微信公众号
  • 微信社群