单项选择题

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... Fossil fuels burned to (8) cars and trucks, (9) homes and businesses, and power factories are (10) for about 98% of US carbon dioxide emissions, 24% of methane emissions, and 18% of nitrous oxide emissions. Increased agriculture, deforestation, (11) , industrial production, and mining also contribute a significant (12) of emissions. In 1997, the United States (13) about one-fifth of total global greenhouse gases.
The 20th century’ s 10 warmest years all (14) in the last 15 years of the century. Of these, 1998 was the warmest year on (15) . The snow (16) in the Northern Hemisphere and floating ice in the Arctic Ocean have decreased. Globally, sea level has (17) 4～8 inches over the past century. Worldwide precipitation over land has increased by about one percent. The (18) of extreme rainfall events has increased throughout much of the United States.
Increasing concentrations of greenhouse gases are likely to (19) the rate of climate change. Scientists expect that the average global surface temperature could rise 1～4.5(0.6～2.5℃) in the next fifty years, and 2.2～10(1.4～5.8℃) in the next century, (20) significant regional variation. Evaporation will increase (21) the climate warms, (22) will increase average global precipitation. Soil moisture is likely to decline in many regions, and (23) rainstorms are likely to become more frequent. Sea level is likely to rise two feet along most of the US coasts. (24) of climate change for specific areas are much less reliable than (25) ones, and it is unclear (26) regional climate will become more (27) .

26().

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