温馨提示
更多 [南京托福暑假培训学校] 资讯、更多优惠活动！ 请联系在线客服！！
| 雅思（学术类） | 新托福 | 能力水平 |
|---|---|---|
| 9 | 118-120 | 能够完全驾驭英语，对语言理解恰当，准确，熟练 |
| 8.5 | 115-117 | 能够英语运用自如，能把复杂的细节性问题解释清楚 |
| 8 | 110-114 | 能够很好地运用英语，不熟悉语境的情况下可出现误解。 |
| 7.5 | 102-109 | 可存在很少的错误或者用词不准确 |
| 7 | 94-101 | 有效运用英语，语言上允许偶尔误解和不准确，但能理解详细的推理 |
| 6.5 | 79-93 | 能够有效运用英语，能够掌握相对复杂的 |
| 6 | 60-78 | 语言中有不准确的情况发生，但在熟悉情况下，掌握较为复杂的英语 |
| 5.5 | 46-l59 | 能较好运用部分英语，可以进行基本沟通 |
| 5 | 35-45 | 在熟悉的情况下具备基本的理解能力，在理解和表达上有一定的认知 |
| 4.5 | 31-34 | 可以听懂稍微简单的句型内容，但无法有效沟通 |
| 0-4 | 0-31 | 只能说出个别单词，无法用英语流畅沟通 |
温馨提示
更多 [南京托福暑假培训学校] 资讯、更多优惠活动！ 请联系在线客服！！
新托福预备钻石课程180731晚间班
【适合人群】
词汇量在2000-2500，初三至高一英语程度或同等水平
【课程介绍】
课程简述：该课程适合能阅读中等长度的文章，但无法摸透其辩论性的观点；表达中的语法错误虽少，但表达方式仍较为幼稚；很难听懂中级听力的学生。 教学承诺：词汇量在2000-2500，初三至高一英语程度或同等水平
温馨提示
更多 [南京托福暑假培训学校] 资讯、更多优惠活动！ 请联系在线客服！！
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in the atmosphere warm a planets lower atmosphere and surface. It was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896.Existence of the greenhouse effect as such is not disputed, even by those who do not agree that the recent temperature increase is attributable to human activity. The question is instead how the strength of the greenhouse effect changes when human activity increases the concentrations of greenhouse gases in the atmosphere.
Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F).[20]The major greenhouse gases are water vapor, which causes about 36–70 percent of the greenhouse effect; carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which causes 4–9 percent; and ozone (O3), which causes 3–7 percent.Clouds also affect the radiation balance, but they are composed of liquid water or ice and so are considered separately from water vapor and other gases.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The concentrations of CO2 and methane have increased by 36% and 148% respectively since the mid-1700s.[24] These levels are much higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores.Less direct geological evidence indicates that CO2 values this high were last seen about 20 million years ago.[26] Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, particularly deforestation.
CO2 concentrations are continuing to rise due to burning of fossil fuels and land-use change. The future rate of rise will depend on uncertain economic, sociological, technological, and natural developments. Accordingly, the IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.Fossil fuel reserves are sufficient to reach these levels and continue emissions past 2100 if coal, tar sands or methane clathrates are extensively exploited.
The destruction of stratospheric ozone by chlorofluorocarbons is sometimes mentioned in relation to global warming. Although there are a few areas of linkage, the relationship between the two is not strong. Reduction of stratospheric ozone has a cooling influence, but substantial ozone depletion did not occur until the late 1970s.Tropospheric ozone contributes to surface warming.
》》更多托福阅读辅导
更多托福资讯请访问》》》新东方网TOEFL频道
(责任编辑：申月月)
我要报班》》新东方托福辅导课程
相关推荐
相关推荐
体验课预约试听
倒计时
课程热线：
客服在线时间：早上9点~下午6点，其他时间请在线预约报名或留言，谢谢！
个试听名额
