Supply and demand is perhaps one of the most basic concepts of economics and it is the backbone of a market economy. Demand refers to how much of a product or service is desired by buyers. The quantity demanded is the amount of a product people are willing to buy at a certain price; the relationship between price and quantity demanded is known as the demand relationship. Supply represents how much the market can offer. The quantity supplied refers to the amount of a certain goods producers are willing to supply when receiving a certain price. The relationship between price and how much of a goods or service is supplied to the market is known as the supply relationship. Price, therefore, is a reflection of supply and demand. The law of demand states that, if all other factors remain equal, the higher the price of a product, the fewer people will demand that product. The amount of goods that buyers purchase at a higher price is less as the price of a product goes up, so does the opportunity cost of buying that product. Like the law of demand, the law of supply shows the quantities that will be sold at a certain price. But unlike the law of demand, the supply relationship shows an upward slope. This means that the higher the price, the higher the quantity supplied. Producers supply more at a higher price because selling a higher quantity at a higher price increases the whole income. Now that we know the laws of supply and demand, let's turn to an example to show how supply and demand affect price. Imagine that a CD of your favorite band is sold for $20. Because the record company's previous analysis showed that consumers will not demand CDs at a price higher than $20, only ten CDs were sold because the opportunity cost is too high for suppliers to produce more. If, however, the ten CDs are demanded by 20 people, the price will then rise. As a result, the rise in price should cause more CDs to be supplied as the supply relationship shows that the higher the price, the higher the quantity supplied. If,... The text is written mainly _ . A) to persuade people to buy more products B) to let people know more about a CD C) to explain the relationships between demand, supply and price D) to tell people how to buy things reasonably
C
(Question)
Canadian short story writer Alice Munro won the Nobel Prize for Literature. Eighty-two-year-old Munro is only the 13th woman to win the 112-year-old prize. Munro didn't publish her first collection of short stories until she was 37 years old, but her stories have always been well-received. Lots of her stories share similar themes and characters, but each story has its own twists and turns. Even though she's won Canada's most famous literary award, the Giller Prize, twice, winning the Nobel Prize for Literature is the cherry on top of Munro's career. "It brings this incredible recognition, both of her and her career, and of the dedication to the short story," said one person. Along with the well-respected title comes 1.3 million dollars.Munro said everything was "so surprising and wonderful" and that she was "dazed by all the attention and affection that has been coming my way." Munro knew she was in the running-she was named the second-most likely person to win this year's prize, after Haruki Murakami of Japan-but she never thought that she would win. Munro's win also represents the long way Canadian writers have come."When I began writing there was a very small community of Canadian writers and little attention was paid by the world.Now Canadian writers are read, admired and respected around the globe," Munro said on Thursday. She is technically not the first Canadian to win the Nobel Prize for Literature, but many like to think that she is.In 1976 Saul Bellow, who was born in Quebec but moved to Chicago when he was still a child, won the prize.Even though he was born in Canada, he is mostly considered to be an American writer. "This is a win for us all.Canadians, by our very nature, are not very nationalistic," said Geoffrey Taylor."But things like this suddenly make you want to find a flag." She wasn't sure if she would keep writing if she won the prize, saying that it would be "nice to go out with a bang.But this may change my mind." What does the passage mainly tell us? A) How Alice Munro wins the Nobel Prize B) An introduction to the Nobel Prize in Literature C) Alice Munro wins the Nobel Prize in Literature D) A world famous writer, Alice Munro
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C
Ques:Ask runners why they run and you'll get a variety of answers; to stay healthy or to feel better. Some have an even bigger reasonto stay calm or out of prison. But Back on My Feet puts recovering addicts and the homeless on the road to a brighter future, starting with a simple step; attending group runs three tunes a week. At 5:30 a.m. on a hot July day, Back on My Feet's Team Brooklyn gathered in a parking lot. After a round of hugs and some warm-up, the group of eight volunteers and seven residents set out on a run to nearby Prospect Park. Some ran three miles, some longer, but the goal for all was to finish as a team "It's helping me put my life back together," said Jimmy, a 58-year-old cancer survivor who was homeless and a former alcohol addict. "It's healthy. It makes me feel good inside," adds Jimmy. Many are skeptical about the idea of homeless runners, according to Anne Mahlum, who founded Back on My Feet in 2007 after starting a running club for men at a shelter near her Philadelphia home. They did want to run, and in just six years, Mahlum's small running club has expanded to 10 cities around the country, and 388 active members. The only requirement for joining, besides wanting to, is insisting on at least 30 days."The first day we give them new shoes and Back on My Feet shirts," Mahlum says. "Then they run a mile the first day. And then gradually we'll encourage them to build goals. "After 30 days,residents gain access to services like financial aid,housing assistance and employment opportunities through Back on My Feet's partners. In its first year, the New York chapter has seen 41 members obtain employment, 34 gain housing and 50 work in job-training programs. That's not to say it's always easy. "I wanted to quit. But then I started to push myself,"said Adel, 39, who began running in March. "Now I would love to run a 10-mile run. Or maybe a marathon one day, who knows. I ran this far, so why not?" Members of Back on My Feet must . A) run on weekends B) run the same distance C) attend group runs D) keep the same speed

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C