TASK DEFINITION: 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.
PROBLEM: Context: Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found. Electrons are tiny, negatively charged particles in an atom that move around the positive nucleus at the center. Energy levels are a little like the steps of a staircase. You can stand on one step or another but not in between the steps. The same goes for electrons. They can occupy one energy level or another but not the space between energy levels. The model in the Figure 1.1 shows the first four energy levels of an atom. Electrons in energy level I (also called energy level K) have the least amount of energy. As you go farther from the nucleus, electrons at higher levels have more energy, and their energy increases by a fixed, discrete amount. Electrons can jump from a lower to the next higher energy level if they absorb this amount of energy. Conversely, if electrons jump from a higher to a lower energy level, they give off energy, often in the form of light. This explains the fireworks pictured above. When the fireworks explode, electrons gain energy and jump to higher energy levels. When they jump back to their original energy levels, they release the energy as light. Different atoms have different arrangements of electrons, so they give off light of different colors. Q: In the atomic model Figure 1.1, where would you find electrons that have the most energy? A: Electrons with the most energy would be found in energy level IV. The smallest atoms are hydrogen atoms. They have just one electron orbiting the nucleus. That one electron is in the first energy level. Bigger atoms have more electrons. Electrons are always added to the lowest energy level first until it has the maximum number of electrons possible. Then electrons are added to the next higher energy level until that level is full, and so on. How many electrons can a given energy level hold? The maximum numbers of electrons possible for the first four energy levels are shown in the Figure 1.1. For example, energy level I can hold a maximum of two electrons, and energy level II can hold a maximum of eight electrons. The maximum number depends on the number of orbitals at a given energy level. An orbital is a volume of space within an atom where an electron is most likely to be found. As you can see by the images in the Figure 1.2, some orbitals are shaped like spheres (S orbitals) and some are shaped like dumbbells (P orbitals). There are other types of orbitals as well. Regardless of its shape, each orbital can hold a maximum of two electrons. Energy level I has just one orbital, so two electrons will fill this energy level. Energy level II has four orbitals, so it takes eight electrons to fill this energy level. Q: Energy level III can hold a maximum of 18 electrons. How many orbitals does this energy level have? A: At two electrons per orbital, this energy level must have nine orbitals. Electrons in the outermost energy level of an atom have a special significance. These electrons are called valence electrons, and they determine many of the properties of an atom. An atom is most stable if its outermost energy level contains as many electrons as it can hold. For example, helium has two electrons, both in the first energy level. This energy level can hold only two electrons, so heliums only energy level is full. This makes helium a very stable element. In other words, its atoms are unlikely to react with other atoms. Consider the elements fluorine and lithium, modeled in the Figure 1.3. Fluorine has seven of eight possible electrons in its outermost energy level, which is energy level II. It would be more stable if it had one more electron because this would fill its outermost energy level. Lithium, on the other hand, has just one of eight possible electrons in its outermost energy level (also energy level II). It would be more stable if it had one less electron because it would have a full outer energy level (now energy level I). Both fluorine and lithium are 
 Question: any atom is most stable when its outermost energy level contains

SOLUTION: as many electrons as it can hold.

PROBLEM: 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?

SOLUTION: mad about mahjong

PROBLEM: Context: The scene opens with Ellen (Sharon Stone) riding across the prairie toward a town, when an idiot digging multiple holes looking for his gold, shoots at her. She falls off her horse and knocks him out as he checks to see if she is dead. After chaining him to his wagon, she continues into town. A large, single elimination gun fighting tournament is about to begin and she is looking for revenge on the man ( Herod/Gene Hackman) who killed her father. She arrives at the bar/hotel. Ace Hanlon shows off his deck of cards with an ace for every man he has killed. Soon, the saloon comes to life as Scars who just got out of jail, comes back to settle a score. He makes a move on Ellen, and she tells him to take a bath. Scars gets angry and kicks the blind boy's peddling wagon, as he was talking to Ellen. Later at the drafting of the tournament, the saloon owner is to sign up 16 gunfighters. Among them are The Kid (Leonardo DiCaprio), Sgt. Cantrell (Kieth David), Cort, the marksman and odds on favorite (Russell Crowe) though he was signed up against his will. Cort was an outlaw who became a preacher and built a mission. Since he was one of Herod's partners in crime, Herod now wants Cort dead. Also in the contest is Ace Hanlon ( Lance Herrickson), A Swedish Champ. and of course Herod. Anyone can challenge anyone, and each fighter must accept the first challenge. Ellen is challenged by the idiot who was digging for his lost gold. But up first was the Kid and he quickly shot the Swede and the winner is the last standing.The Swede was shot twice and then threw his gun down. Also winning, were Stg. Cantrell, Scars, and Eugene the scumbag. Herod has challenged Ace(because he thinks Ace was hired to kill him) and one of Herod's men challenged Cort. After Rusty, another of Herod's men has beaten Cort up as he was chained to a fountain in the middle of the village. Herod has Cort released so that he can go to the Kid's gun store. Herod gives Cort the cheapest gun in the place. The Kid also has told everyone that Herod was his father. Herod denies that and rubs it in the Kid's face. Then Cort went out to a fight that he refused to be in. But when the clock stuck, only one bullet was fired. Herod's man fell to the ground. Many claimed to be the fastest gun in town, like the Kid, Herod, and Ace, but all knew that Cort was the fastest. Next, Ace is bragging and doing gun tricks. It is time for he and Herod to face each other. Herod proves that Ace has been lying about all of his kills. The clock strikes and Herod blows Ace's right thumb off. Then he shoots Ace's left hand. Then after mocking Ace some more, Herod's shoots him in the chest. Then Ellen wins her first fight with Cort's help. The next day, Herod invites Stg. Cantrel to his home. He tells the Sgt, that he knows that he was the hired hand and not Ace. The Sgt. does not tell him much and the challenge has been issued. Later, Herod changes the rules and now all fights are to the death. Herod takes down Cantrell, and then scolds the crowd for hiring him. Meantime, Eugene the scum bag is heard upstairs molesting a girl. He comes downstairs and brags about it. Ellen attacks him from behind and the two scream at each other until the challenge is made. though it is pouring outside, The two come out firing and Eugene gets his manhood shot off. The rules have changed and the winner is the last alive. Ellen couldn't finish him off, so she returned to the bar. Eugene comes in and shoots her glass. Then Ellen empties her gun into him.Though Herod tells the Kid to quit, that he has proven his point, the Kid stays in and takes 
 Question: Who has Herod challenged before challenging The Lady?

SOLUTION:
ace