摘要: 二氧化物

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Human activity has influenced not only the environment we live in, but also some parts of the world no one has been to. Increased levels of carbon dioxide (二氧化碳) in the atmosphere produced by forest burning, automobiles and industry has led to rapid changes in untouched areas of South America's Amazonian rainforest.

The latest results of a study carried out by US and Brazilian scientists show that carbon dioxide levels have risen by 30 per cent in the last 200 years. The gas is used in photosynthesis (光合作用), the

process by which organisms (生物体)change sunlight into energy.

The higher level of carbon dioxide is causing some trees in the Amazonian rainforest to grow faster and die sooner. As a result, certain plants and animals could disappear.

"Tropical rainforests are famous for having lots of special species (种类)," said William Laurance, leader of the research team. "If you change the tree types, then other species particularly animals that feed on the trees, will change as well."

With certain trees growing faster and dying sooner, the plants that live in their shadows are also threatened. Alexandre Oliveira, another member of the research team, explained, "Large, fast growing trees are winning at the expense of smaller trees that live lower down."

The team has spent the last 20 years following the life patterns (模式) of 14,000 trees spread across an area of 190 square kilometers. They have found that the people responsible for the death of the rainforests are not just hunters and those who cut down trees. Something as innocent(清白的) as driving the car to the shops instead of walking can also cause damage.

7. What does harm to our environment according to the passage?

A. Dying animals.B. Human activity.C. Chemical plants.D. Burning houses.

8. The reason for South America's Amazonian rainforest to grow faster and die sooner is________.

A. that levels of carbon dioxide haverisen

B. that people burn plenty of rainforests freely

C. that the gas can change sunlight into energy

D. that tropical weather changes from time to time

9. The passage is most probably________.

A. government news

B. a wild experiment

C. a geography book

D. an experimental report

10. From the passage we can infer that ________.

A. those who go camping in forests shouldn't be responsible

B. innocent people should drive cars into rainforests

C. those who cut down trees will be punished

D. people who cut down trees should plant more trees

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