Against the supposition（假设）that forest fires in Alaska, Canada and Siberia warm the climate, scientists have discovered that cooling may occur in areas where burnt trees allow more snow to mirror more sunlight into space.
This finding suggests that taking steps to prevent northern forest to limit the release of greenhouse gases may warm the climate in northern regions. Usually large fires destroyed forests in these areas over the past decade. Scientists predict that with climate warming, fires may occur more frequently over next several centuries as a result of a longer fire season. Sunlight taken in by the earth tends to cause warming, while heat mirrored back into space tends to cause cooling.
This is the first study to analyze all aspects of how northern fires influence climate. Earlier studies by other scientists have suggested that fire in northern regions speed up climate warming because greenhouse gases from burning trees and plants are released into the atmosphere and thus trap heat.
Scientists found that right after the fire, large amounts of greenhouse gases entered the atmosphere and caused warming. Ozone（臭氧）levels increased, and ash from the fire fell on far-off sea ice, darkening the surface and causing more radiation from the sun to be taken in. The following spring, however, the land within the area of the fire was brighter than before the fire, because fewer trees covered the ground. Snow on the ground mirrored more sunlight back into space, leading to cooling.
“We need to find out all possible ways to reduce the growth of greenhouse gases in the atmosphere.” Scientists tracked the change in amount of radiation entering and leaving the climate system as a result of the fire, and found a measurement closely related to the global air temperature. Typically, fire in northern regions occurs in the same area every 80 to 150 years. Scientists, however, found that when fire occurs more frequently, more radiation is lost from the earth and cooling results. Specifically, they determined when fire returns 20 years earlier than predicated, 0.5 watts per square meter of area burned are soaked up by the earth from greenhouse gases, but 0.9 watts per square meter will be sent back into space. The net effect is cooling. Watts are used to measure the rate at which energy is gained or lost from the earth.
【小题1】According to the new findings, taking steps to prevent northern forest fires may _______.
   

Hey, Mr. and Ms．Unluckiness and Unhappiness! Terrorism, the war, the economic crisis and unemployment are at your door．Are you afraid of them? Well, don’t be! America is a happy land．The Smiley Face icon proves this in towns all over the country．

The tallest structure—the steel water tower—is often painted bright yellow, in a circle containing a pair of black dots for eyes and an upturned（朝上的）line for a mouth: the unforgettable smile．Most towns decorated their spheroid （or cylindrical） water storage tanks in the 1970s, when Smiley was still conceptually fresh．As a "safe" counterculture symbol, with absolutely no bite, the Smile Face water tower was a low cost way to radiate sunny greetings to travelers and locals．Calumet City, Illinois claims to have been the first, when 8-year old resident Kim Fornero sent a letter to the city council in late 1972 suggesting a smile face would be more fun to look at than a plain old water tower．

In the 1980s, with the paint on the water tower fading, residents of Calumet City decided to make the face their own．They repainted the tower, and a Happy Cook Restaurant and Smiley Face Inn appeared on the highway outside the town, ready to make you smile! Local businessmen printed the Smiley icon on their business cards, and displayed Smiley Face souvenirs in shop windows．

By the late 1990s, the survival of the Smiley Face water tower was assured．It didn’t matter why the face had been painted there—it was now a part of history．In May 2009, the town again celebrated its Smiley Face water tower as a symbol of hope for a better tomorrow．

1．The author mainly wants to tell readers that the symbol asks them to        .

       A．greet people politely                             B．deal with their problems

       C．enjoy themselves                                 D．forget the past

2．The underlined word “icon ” in the first paragraph probably means         .

       A．beautiful picture   B．building               C．image                  D．valuable painting

3．Why did Calumet residents accept the tower happily?

       A．It set a good example to them.

       B．It made them work harder.

       C．They wanted to think it for supplying water.

       D．They wanted to make the Smiley Face their own.

4．From the text we learn that the Smiley Face water tower      .

      A．was based on a painter’s inspiration

       B．is a symbol of the prosperity of the town

       C．is meant to give people hope for a better future

       D．was created in 1972 by the city council, just for fun

When we walk on a street or sit down to have a cup of coffee in a small café in Shanghai, we will often see foreign faces at every turn. Today, foreigners do not come to Shanghai to seek adventures, as they did in the old days, or arrive in the city for a short visit, as some did when China just carried out the opening-up. Instead, many foreigners come to Shanghai to settle in the city. They are attracted by the life in Shanghai and choose to stay in the city. Their stay has made Shanghai more like an international city.
Early in the 1990s, a group of Western-style buildings emerged at the Gubei New District in the southwestern part of the Hongqiao Development Zone in Shanghai. The Western-style buildings, marked by their great arches and the typical flavors of the unique European style, appealed to many foreigners and become their favorite choice when they came to live or work in Shanghai. Foreigners gathered in the zone, enjoying their quiet life there.
As the city further develops, more and more foreigners choose to live in the downtown area where most native Shanghai people live. They live close to local residents and gradually become interated(一体化)into the local life—they learn to cook local dishes, they learn to speak the Shanghai dialect and they celebrate traditional Chinese holidays together with native people. Their lifestyle is becoming more and more similar to that of local residents.
In the past, foreigners that came to Shanghai were mostly representatives(代表)sent to work in the city. Today, however, many foreigners that live in the city are students, business starters or ordinary people. Related information shows that there are more than 50,000 foreigners living and working in Shanghai.
【小题1】Foreigners used to come to Shanghai to_____.