- UID
- 1461121
- 在线时间
- 小时
- 注册时间
- 2020-7-10
- 最后登录
- 1970-1-1
- 主题
- 帖子
- 性别
- 保密
|
Passage 219Ecologists had assumed that trees in the consistently warm tropics grew at a slow but steady rate, unvarying from year to year. However, a study at La Selva, Costa Rica, showed that trees grew less in hotter years and more in cooler ones: between 1984 and 2000, dramatic differences occurred in the six species of trees studies, with trees adding twice as much wood in some cooler years as they did in the scorching(酷热的) El Nino year of 1997-1998. Because tree growth is an index of the balance between photosynthesis, in which trees absorb carbon dioxide (CO2) from the atmosphere and release oxygen, and respiration, in which the opposite occurs, the La Selva data were the first hint that rapidly rising global temperatures, driven by human-generated emissions of CO2, may be pushing tropical forests to release more CO2, thereby intensifying global warming. This raised serious questions about a popular theory that tropical forests act as a sponge, soaking up much of the excess CO2 that humans pump into the atmosphere. The La Selva data are consistent with a model of global CO2 flux developed by Keeling, who concluded that the amount of CO2 taken up in tropical landmasses rose in cooler years and fell in hotter ones, accounting for year-to-year changes in the amount of CO2 that stays in the atmosphere.
3. The passage suggests that as temperatures rise, trees in the tropical regions (D)
A. continue to grow at a slow but steady rate
B. grow less and intensify photosynthesis
C. emit more CO2 and oxygen
D. increase overall respiration and decrease overall photosynthesis
E. grow more and absorb more CO2
这是我自己列的一个小框架:
| | | Reason and Evidence Stated | | Trees Grew less Less wood Infers less photosynthesis and more respiratory | Trees Grew more More wood Infers more photosynthesis (where CO2 is absorbed) | “However, a study..1997-1998” | Challenges the “sponge theory” that tropical forests soak up CO2 | Release more CO2 and intensify global warming | | “La Selva Data” Consistent with Keeling’s model of global CO2 |
-1 第三问中D选项的"increase overall respiration"是如何推断出来的呀?读完文章,我怎么觉得temperature rise这种情况只能推断出decrease in overall photosynthesis? 于是我就在A和D中纠结选了A...
-2 划线的那一部分我好像没有怎么看明白,求翻译
|
|