Question

The planet is getting greener, and we are responsible. Carbon dioxide generated by human activities is promoting photosynthesis (光合作用) and causing a beneficial greening of the Earth’s surface.

For the first time, researchers claim to have shown that the increase in plant cover is due to this “CO2 fertilisation (肥沃化) effect” rather than other causes. However, it remains unclear whether the effect can reduce any negative effects of global warming, such as the spread of deserts.

To home in on the effect of CO2, Randall Donohue of Australia’s national research institute, the CSIRO in Canberra, monitored vegetation (植被) at the edges of deserts in Australia, southern Africa, the US Southwest, North Africa, the Middle East and central Asia. These are regions where there is plenty of warmth and sunlight, but only just enough rainfall for vegetation to grow, so any change in plant cover must be the result of a change in rainfall patterns or CO2 levels, or both.

If CO2 levels were constant, then the amount of vegetation per unit of rainfall ought to be constant, too. However, the team found that this figure rose by 11 per cent in these areas between 1982 and 2010, mirroring the rise in CO2 emissions (排放). Donohue says this lends strong support to the idea that CO2 fertilization drove the greening.

The extra plant growth could have knock-on effects on climate, Donohue says, by increasing rainfall, affecting river flows and changing the likelihood of wildfires. It will also absorb more CO2 from the air, potentially damping down (抑制) global warming but also limiting the CO2 fertilization effect itself.

Donohue cannot yet say to what extent CO2 fertilisation will affect vegetation in the coming decades. But if it proves to be significant, the future may be much greener.

1.According to the author, the increase in plant cover _____.

A. will speed up global warming

B. results from human activities

C. will stop the spread of deserts

D. promotes the CO2 fertilization effect

2.What does the underlined phrase “To home in on” in Para 3 probably mean?

A. To hold back. B. To cut down.

C. To improve. D. To observe.

3. The amount of vegetation in those monitored areas rose with _____.

A. the rise in CO2 emissions B. annual rainfall

C. the temperatures around D. the amount of sunlight

4.What’s the best title of the text?

A. More rainfall, less CO2 emission

B. How to deal with carbon emissions

C. Positive effects of global warming

D. CO2 emission making Earth greener

Answer 1

1.B

2.D

3.A

4.D

【解析】本文是一篇说明文。我们生活的地球的植被越来越茂盛。研究人员研究发现，这些植物越来越绿的原因不是因为别的，正是因为二氧化碳肥沃化效应。

1. Carbon dioxide generated by human activities is promoting photosynthesis (光合作用) and causing a beneficial greening of the Earth’s surface.由人类活动产生出的二氧化碳正在促进光合作用，使得地球表面绿化。故选B

2. home in on the effect of CO2, …monitored vegetation (植被) at the edges of deserts in Australia, southern Africa, the US Southwest, North Africa, the Middle East and central Asia.监管澳大利亚、南非、北美西南部、北非、中东和中亚的沙漠边缘的植被。我们根据该句子结构可知道，划线句是一个动词不定式做目的状语，句子的谓语部分是对达成目的具体的方法的描述。由monitored可知意思为监管、监控。故选D

3. However, the team found that this figure rose by 11 per cent in these areas between 1982 and 2010, mirroring the rise in CO2 emissions (排放).然而，这个团队发现在1982年到2010年这些地区的反应二氧化碳排放的数据上升了11个百分点。故选A

4.

考点：考察说明文阅读。