Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Ex Input:
Context: Yosemite Sam runs for mayor of a small town, and in his campaign speech, he makes several empty promises like "There's enough fresh air and sunshine in this great country of ours for everybody - and I'll see to it that you'll get your share!" As the speech continues, we see that Bugs Bunny is drinking carrot juice beneath Sam's podium. When Sam pledges to make good on a previous promise "to rid this country of every last rabbit", Bugs decides that the best way to fight him is to run for mayor against him. Bugs soon tries to win the townspeople over with Theodore Roosevelt's famous quote "I speak softly, but I carry a big stick!", which leads Sam to declare "I speak LOUD and I carry a BIGGER stick, and I use it too!".Sam has several tricks up his sleeve, but Bugs finds a way to answer every one. When Sam steals Bugs' cigar stand, Bugs switches the "Smello" cigars he had been selling for five-cent "Atom" explosive cigars (the box includes the slogan "You Will Get A BANG Out of This"). Sam gives a cigar to a man, but after the cigar explodes, the man punches Sam in the face. Sam then sends a box full of "assorted" picnic ants to steal all of the food at Bugs' picnic, which leads Bugs to hide a stick of dynamite in a watermelon being stolen.Sam rigs up a cannon at the front door of Bugs' headquarters, then turns up at the back door greeting Bugs in a friendly manner. When he taps his foot on the floor, he suggests that someone is knocking at the front door, and Bugs leaves Sam and goes to answer it, but this plan backfires when Bugs tells Sam that it was someone for him, and she said to mention St. Louis, which leads Sam to think that a pretty girl named Emma is there. Sam runs to the front door, opens it and gets shot by his own cannon.Sam's next challenge is to ask Bugs if he can "play the pi-anna". Bugs accepts, so Sam rigs an explosive in a particular piano key, and presents the piano to Bugs with a sheet of music containing the tune "Those Endearing Young Charms". When Bugs plays the tune, he deliberately hits a sour note that avoids the explosive key. When Bugs gets the note wrong a second time, it infuriates Sam, who shows Bugs how to play the tune correctly, and falls for his own trap by playing the note that sets off the explosion.After this, Sam and Bugs engage in a short pursuit through the streets of the town, which ends when they come across a parade that celebrates the newly-elected mayor - a chestnut horse who rides in a car bearing a sign that says "Our New Mare" - a literal "dark horse" candidate. This leads Bugs to make the odd suggestion to Sam to play a game of Russian Roulette and hand a gun to Sam. Sam agrees to the game, points the gun to his head, closes his eyes, pulls the trigger and hears the click of an empty barrel. Sam then passes the gun to Bugs, who points it to his head, closes his eyes and pulls the trigger as the film irises out into black in the middle. We hear the sound of a gunshot, then the film irises in on the left hand side to reveal a ducking Bugs, who holds a smoking gun as he says "I missed". A second iris appears on the right hand side to show Sam, who appears scorched and is missing his hat as a result of being hit in the face by Bugs' wayward shot. After Sam says "I hate that rabbit!", both sides of the film iris out for good.
Question: Who was the "dark horse" candidate?

Ex Output:
the newly-elected mayor - a chestnut horse

Ex Input:
Context: Mahjong, that favorite pastime of "old folks" in Shanghai, is finding a new audience among younger players, and many university students are becoming mad about this traditional Chinese game. Students at Fudan University have even formed a Mahjong club. This resurgence of the game, however, is not without its critics. Some people still associate the game with gambling and for many years Mahjong was banned in China. One critic, surnamed Meng, was quoted as saying, "Mahjong is a bad custom that will distract students from studies." But Yu Guangyuan, former vice-president of the Chinese Academy of Social Sciences , says Mahjong is a "healthy, scientific, friendly mind game." Mr. Yu's opinion seems to be shared by the majority of Chinese. They see the game as an activity that requires great concentration and intellectual skill. They also see the game as an important part of Chinese culture and a pastime that brings family and friends closer together. This Spring Festival many families will no doubt spend hours around the Mahjong table getting reacquainted with each other. For them, playing Mahjong is a way of spending quality family time. No one knows who invented Mahjong. Some say it was Confucius, others say the current form of the game was developed right here in Shanghai in the late19th century. It is certainly because of Shanghai that the game enjoys its worldwide popularity. It was brought to America in the 1920s and has since spread throughout Europe and other parts of Asia. There is now a World Championship of Mahjong which is held every year. This year's championship was held in Chongqing and attracted players from America, Europe and Russia, as well as students from Peking University, Tshinghua University and Nankai University. There was no prize money, but the players delighted in using their wits and their understanding of statistics and probability theory to defeat their clever opponents. Of course, Mahjong doesn't have to always be that intense. For young people it can be a way to relax and to socialize, a chance to get away from their computers and talk to other people face to face. So, this Spring Festival, why not get out the "old folks" tiles: it's good to be mad about Mahjong!
Question: What is the best title of the passage?

Ex Output:
mad about mahjong

Ex Input:
Context: In the mid 1900s, people were startled to see the Cuyahoga River in Cleveland, Ohio, burst into flames! The river was so polluted with oil and other industrial wastes that it was flammable. Nothing could live in it. You can see the Cuyahoga River in Figure 21.16 Disasters such as rivers burning led to new U.S. laws to protect the water. For example, the Environmental Protection Agency (EPA) was established, and the Clean Water Act was passed. Now, water is routinely tested. Pollution is tracked to its source, and polluters are forced to fix the problem and clean up the pollution. They are also fined. These consequences have led industries, agriculture, and communities to pollute the water much less than before. Most water pollution comes from industry, agriculture, and municipal sources. Homes are part of the municipal source and the individuals and families that live in them can pollute the water supply. What can you do to reduce water pollution? Read the tips below. Properly dispose of motor oil and household chemicals. Never pour them down the drain. Also, dont let them spill on the ground. This keeps them out of storm sewers and bodies of water. Use fewer lawn and garden chemicals. Use natural products instead. For example, use compost instead of fertilizer. Or grow plants that can thrive on their own without any extra help. Repair engine oil leaks right away. A steady drip of oil from an engine can quickly add up to gallons. When the oil washes off driveways and streets it can end up in storm drains and pollute the water supply. Dont let pet litter or pet wastes get into the water supply (see Figure 21.17). The nitrogen they contain can cause overgrowth of algae. The wastes may also contain bacteria and other causes of disease. Water treatment is a series of processes that remove unwanted substances from water. The goal of water treatment is to make the water safe to return to the natural environment or to the human water supply. Treating water for other purposes may not include all the same steps. Thats because water used in agriculture or industry may not have to be as clean as drinking water. You can see how water for drinking is treated in Figure 21.18. Treating drinking water requires at least four processes: 1. Chemicals are added to untreated water. They cause solids in the water to clump together. This is called coagulation. 2. The water is moved to tanks. The clumped solids sink to the bottom of the water. This is called sedimentation. 3. The water is passed through filters that remove smaller particles from the water. This is called filtration. 4. Chlorine is added to the water to kill bacteria and other microbes. This is called disinfection. Finally, the water is pure enough to drink. Conserving water means using less of it. Of course, this mostly applies to people in the wealthy nations that have the most water and also waste the most. Irrigation is the single biggest use of water. Overhead irrigation wastes a lot of water. Drip irrigation wastes a lot less. Figure 21.19 shows a drip irrigation system. Water pipes run over the surface of the ground. Tiny holes in the pipes are placed close to each plant. Water slowly drips out of the holes and soaks into the soil around the plants. Very little of the water evaporates or runs off the ground. Some communities save water with rationing. Much rationing takes place only during times of drought. During rationing, water may not be used for certain things. For example, communities may ban lawn watering and car washing. People may be fined if they use water in these ways. You can do your part. Follow any bans where you live. Its easy to save water at home. If you save even a few gallons a day you can make a big difference over the long run. The best place to start saving water is in the bathroom. Toilet flushing is the single biggest use of water in the home. Showers and baths are the next biggest use. Follow the tips below to save water at home. Install
Question: process in water treatment in which large particles settle to the bottom of the water

Ex Output:
sedimentation