Unit 11.在历时四年的研究中，科学家调查了地球上的许多生境、物种以及将它们联系起来的生态体系。
For four years the scientists examined the planet’s many habitats and species and the systems that bind them together.2.《千年生态系统评估综合报告》为人们提供了认识生态系统经济价值的全新视角，也为人们尊重和保护地球的生命支持体系提供了新的论据。
The Millennium Ecosystem Assessment Synthesis Report gives people a new insight into the economic importance of ecosystem services and some new and additional arguments for respecting and conserving the Earth’s life-support system.3.科学家认为，水文系统的改变可能导致破坏性洪灾的发生更加频繁和严重。
According to the scientists, changes to water systems may increase the frequency and severity of destructive floods.4.从经济角度看，与那些被用于商业开发的生态系统相比，很多原始生态系统的价值更高。
From an economic perspective, compared with the ecosystems altered for commercial use, many intact ones are more valuable.5.如何在利用地球生态系统提高人类生活水平的同时，缓解该系统所承受的压力，完全取决于人类社会。
It lies within the power of human societies to ease the strain we are putting on the nature services of the planet, while continuing to use them to bring better living standards to all.Unit 21.地球上的石油和天然气供应能维持多久，科学家和企业界人士对此各持己见。
Scientists and industry experts may disagree over how long the world’s supply of oil and nature gas will last.2.一般来说，再生能源比传统生产的能源要贵些，然而替代能源有助于减少污染，保护矿物燃料。
While renewable energy is generally more expensive than conventionally produced supplies, alternative power helps to reduce pollution and to conserve fossil fuels.3.如今在市场上，传统的光感太阳能装置能把11%至13%的阳光转化成能源。
Most traditional photovoltaic solar units on the market today convert between 11 and 13 percent of the sun’s light into energy.4.4美分。
Compared to other renewable energy sources, wind power competes with conventional energy at a price less than 4 cents per kilowatt-hour.5.虽然在美国几乎没有家庭利用风力发电，但许多能源公司允许消费者选择风力发电厂或其他再生能源产生的电力。
While few homes generate their own wind power in the U.S., many power companies allow consumers to opt for power generated at a wind plant or other renewable source.Unit 31.当温度低于零摄氏度或高于43摄氏度时，大多数的植被都会受到伤害甚或死亡。
If it falls below 1°Celsius or rise above 43°Celsius,serious injury or death results for most vegetation.2.从树和灌木的枝和叶我们就可以看出它们对环境的适应性。
这种适应性使之能获得最大限度的光和空气。
The stems and leaves of trees and shrubss show us some of the adaptations that enable a plant to get the maximum amount of light and air.3.它们没有叶绿素，靠其他动物或植物产生的有机物来生存，凡是在菌类植物茂盛的地方都可以找到这些有机物。
They have no chlorophyll,but subsisit on organic matter, produced by animals or other plants, that may be found wherever the fungi flourish.4.在海洋深处和湖泊，水潭底部的植物接受的阳光也是最少的，因为这些地方的光照很弱，甚至没有阳光。
Plants also receive a minimum of light in the depths of the sea or at the bottom of lakes and pools, since sunlight is weak or absent there. 5.人们认为它们在吸收了光之后，就把光能转化成了叶绿素，再进行光合作用。
It is suspected that after they absorb light,they transmit the energy from this light to chlorophyll,for photosynthesis.Unit 41.植物蒸腾作用消耗一部分降水，将它返回大气中。
部分水分保存在土壤或其他植物生长媒介中，其余部分则徐徐进入城市排水系统，减少大量降雨突至时城市水系承受的压力，而扩展城市水系则需要很高的费用。
Some of that water is lost when the vegtation transpires,or“exhales”the water back into the atmosphere. Some water is retained in the soil or other growing medium. The rest enters the urban rainwater drainage system in a slow,controlled flow,a process that helps dampen high-volume rainwater surges in urban water systems, which are expensive to expand.2.绿色屋顶能在多大程度上降低能源支出，这取决于屋顶的类型以及所在地区的气候条件。
在气候比较温暖的地区节省开支的可能性最大。
因为绿色屋顶的降温效率要高于采暖效率。
How much a green roof lowers energy costs depends on the type of roof and the climate in which it is installed. Warmer climates offer the greatest saving opportunities, since green roofs are more efficient at reducing air conditioning costs than they are at lowering heating bills.3.虽然绿色屋顶的成本较传统常规屋顶的成本高出1.5至2倍，但支持者认为，即使不考虑节能因素，从长远经济利益懒，屋顶绿化仍很划算。
While the costs of green roofs are one-and-a-half to twice that of conventional roofs,advocates say green roofs make long-term economic sense,even without factoring in energy savings.4.“即使在城市屋顶这样的环境下，我们也能够通过植物的季节变化感受到自然的规律”。
他们在给《国家地理新闻》的电子邮件中写到，“从设计角度看，屋顶绿化可以大大提升美化效果，创造显著生态效益。
”“Nature’s rhythm is made visible by seasonal changes in the vegetation,even in a n urban roof environment,”they wrote in an e-mail to National Geogr aphic News.“In terms of design,roof planting represents a considerable aesthetic improvement and altogether a significant ecological benefit.”5.芝加哥绿色技术中心举办屋顶绿化技术示范园，向开发商、建筑商甚至学生展示相关产品。
该中心同时还是研究中心，邀请主要供应商们到此装配各种各样的绿色屋顶以供观测与比较。
At the Chicago Center for Green Technology, demos showcase green-roof technology to everyone from developers and builders to schoolchildren. The center also serves as a research center, where leading suppliers are invited to install different green-roof plots that are monitored and compared.Unit 51.除此之外还有迅速增加的嵌入式电脑（即那些用于移动电话、加油泵和零售点计价系统中的电脑），其功能和复杂性迅速接近台式电脑。