The second research proved that
A. the life span of trees in the Amazon basin is much longer than others.
B. trees consume carbon dioxide until they die.
C. it takes hundreds of years for trees to purify atmosphere.
D. the carbon that trees consumed may return to the atmosphere in five years.
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What result has the first research found？
A. The roots of trees can save nutrients in the soil.
B. The trees can steady the flow of the rivers.
C. In the next 30 years, the water demand will add by around 50%.
D. Trees trap much less water than they consume in arid areas.
From the last two paragraphs, we know that
A. if each individual counts, one-third of wolves have to be vaccinated.
B. Dr. Haydon proved epidemiologists' standard assumption is right.
C. to vaccinate 10% to 25% of wolves living in the connected meadows is enough.
D. it takes 20 years to reduce risk of extinction if all the wolves are targeted.
Which of the following is true according to the text？
A. South Africa regards planting trees as a basic human right.
B. India had a lot of problems when carrying out the tree-planting schemes.
C. South Africa will punish those forestry companies that cut trees.
D. Indian farmers can drill as many boreholes as they want.
The Ethiopian wolf
A. is facing the risk of extinction as the rarest carnivore.
B. is separated into three groups to achieve survival.
C. lives in narrow valleys in the Bale Mountains.
D. has altogether 350 alive in the world.
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