Part Ⅱ Reading Comprehension (Skimming and Scanning)
Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1. For questions 1-7, choose the best answer from the four choices marked A), B), C) and D). For questions 8-10, complete the sentences with the information given in the passage.
Earth Will Survive Global Warming, But Will We？
The notion that human activity, or the activity of any organism, can affect Earth on a planetary scale is still a hard one for many people to swallow. And it is this kind of disbelief that fuels much of the public skepticism surrounding global warming.
A poll conducted last summer by the Pew Research Center found that only 41 percent of Americans believe the burning of fossil fuels causes global warming. But in a meeting this week in Paris, officials from 113 nations have agreed that a highly anticipated international report will state that global warming was "very likely" caused by human activity. The idea that biology can alter the planet in broad and dramatic ways is widely accepted among scientists, and they point to several precedents throughout the history of life.
The mighty microbes
Human-caused global warming--also called "anthropogenic" global warming--is the latest example of life altering Earth, but it is not the most dramatic.
That title probably goes to the oxygenation of Earth's early atmosphere by ancient microbes as they began to harness the power of sunlight through photosynthesis(光合作用).
Humans "are having a strong effect on global geochemical cycles, but it does not compare at all to the advent of oxygenic photosynthesis," said Katrina Edwards, a geo-microbiologist at the University of Southern California (USC). "That was a catastrophic environmental change that occurred before 2.2 billion years ago which wreaked its full wrath on the Earth system."
Edwards studies another way life impacts the planet in largely unseen ways. She focuses on how microbes living on the dark ocean floor transform. minerals through a kind of underwater power.
"These microbes are completely off radar in terms of global biogeochemical cycles," Edwards told Live-Science." We don't consider them as part of the Earth system right now in our calculation about what's going on, and we don't consider them in terms of how the Earth system will move forward into the future."
These reactions are strongly influenced by life and have been occurring for billions of years, for as long as the oceans have been oxygenated and there have been microbes inhabiting the seafloor, Edwards said.
Creating Earth
On land, microbes, and in particular a form. of bacteria called cyanobacteria (固氮蓝藻), help keep soil in place and suppress dust.
"We'd certainly have more dust storms and it would not be anywhere as nice on Earth if they weren't around," said Jayne Belnap, a researcher with the United States Geological Survey.
Scientists believe the tiny life-forms performed the same roles on early Earth. "One of the big problems for geologists is that, OK, you have this big ball of rock, the soil is weathering out and you have these ferocious winds. What in the world is holding the soil in place as it weathers out of the rocks？" Belnap said in a telephone interview. "Cyanobacteria are also credited with that function."
The microbes anchored soil to the ground; this created habitats for land plants to evolve and eventually for us to evolve. "They literally created Earth in a sense," Belnap said.
"Cyanobacteria are just like 'it'," she continued. "I've been telling everybody to make a small altar and offer sacrifices every night. We owe them everything."
A snowba

American people.
B. People's activity.
C. Industry activity.
Developed countries.