Against the supposition 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 fires 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 the 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 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 the 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... .Earlier studies about northern forest fires _ . A) analyze all aspects of how northern fires influence climate B) indicate that forest fires will pollute the atmosphere C) suggest that people should take measures to protect environment D) suggest that the fires will speed up climate warming
D
(Question)
Well-known companies are powered by their names and reputations. When people walk into a Pizza Hut in Tokyo, Rome, or Miami, they know exactly what they are getting. Through franchising, an investor can make use of this brand power by opening a Pizza Hut of his or her own. The risk is low, and the rewards can be big. No wonder franchising is such a successful business model. Franchising had been around for more than 100 years, but its popularity took off in the 1950s. Leading the trend were fast food restaurant like McDonald's. These days, there are franchises in more than eighty-five industries, including dry cleaning, hotels and supermarkets. It's a very big business. In the US, there are some 760,000 franchises, totaling more than $1.5 trillion in yearly revenues (income). There are two sides in a franchise: the franchisor--the owner of the business system and the franchisee--the person who licenses the system. After signing a "franchise agreement", the franchisee pays a fee. He or she also pays for equipment, supplies, and, if necessary, building costs. The total investment usually ranges from $10,000 to $1,000,000. After the business opens, the franchisee also pays a percentage of sales revenues--called a royalty--to the franchisor. Marking fees must also be paid. In return, the franchisee receives many benefits. Training is among the most common ones. It includes everything from dealing with customers to understanding the company's standards. The franchisor also handles advertising. On top of that, there's the benefit of the brand reputation that the company has built up. All of these benefits make the risk of opening a franchise much smaller than that of starting a business from scratch. However, a franchise can also have drawbacks. If a customer at a single restaurant gets sick, it may hurt every franchise in the system. Running a franchise also means closely following the company's standards. So, one has to give up a degree of independence. You have to do things their way and trust that the system... What is the most important factor to make a franchise successful? A) Brand power. B) Agreement. C) Training. D) Royalty.
(Answer)
A
Birds in cities are damaging their health by trying to sing above the noise of urban life. New research shows that male birds are trying to compete against traffic and city sounds.They are now singing louder and at higher frequencies,which could harm their vocal cords .Some birds are choosing to sing at night instead of during the day.This makes them more open to attack and also creates stress and exhaustion. "The difference between urban and rural birdsong is becoming so big that the two groups could now be unable to communicate.This could lead to inbreeding and a weak gene poo1."said Dr Sue Anne Zollinger of the.University of St Andrews. According to Zollingar,a bird group with a small gene pool might adapt less quickly to new diseases and could be wiped out. A study of the dawn chorus found that birds in Berlin sang up to 14 decibels louder than those in the forest.The birds sang loudest on weekday mornings. "By trying to sing over the sound of the city,birds ale rising vocal injury,"said Zollinger."All this puts the same strain on a bird's vocal cords as when a human need to shout to be heard--except that the birds are doing it all day,every day,"she said. "Singing under such pressure means birds have less control over the sound they produce.Their songs may lose quality and become more rough--sounding."said Zollinger.This could make them appear less attractive to female birds. Mark Constantine,author of The Sound Approach to Birding,said:"Birdsong is important for our quality of life and has been proved to reduce our blood pressure.When we live in the centre of large,urban areas,we get stressed and it's extremely good to have birdsong around us.The impact on humans of birdsong is massive.It harms us,as well as the birds,if their songs become louder and simpler. It requires greatest efforts for birds in cities to sing on _ . A) Monday nights B) Wednesday afternoons C) Saturday Evenings D) Friday mornings
D