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.

[Q]: Context: The smallest planet, Mercury, is the planet closest to the Sun. Because Mercury is so close to the Sun, it is difficult to observe from Earth, even with a telescope. However, the Mariner 10 spacecraft, shown in Figure 1.1, visited Mercury from 1974 to 1975. The MESSENGER spacecraft has been studying Mercury in detail since 2005. The craft is currently in orbit around the planet, where it is creating detailed maps. MESSENGER stands for Mercury Surface, Space Environment, Geochemistry and Ranging. (a) Mariner 10 made three flybys of Mercury in 1974 and 1975. (b) A 2008 image of compiled from a flyby by MESSENGER. As Figure 1.2 shows, the surface of Mercury is covered with craters, like Earths Moon. Ancient impact craters means that for billions of years Mercury hasnt changed much geologically. Also, with very little atmosphere, the processes of weathering and erosion do not wear down structures on the planet. Mercury is named for the Roman messenger god, who could run extremely quickly, just as the planet moves very quickly in its orbit around the Sun. A year on Mercury the length of time it takes to orbit the Sun is just 88 Earth days. Despite its very short years, Mercury has very long days. A day is defined as the time it takes a planet to turn on its axis. Mercury rotates slowly on its axis, turning exactly three times for every two times it orbits the Sun. Therefore, each day on Mercury is 57 Earth days long. In other words, on Mercury, a year is only a Mercury day and a half long! Mercury is close to the Sun, so it can get very hot. However, Mercury has virtually no atmosphere, no water to insulate the surface, and it rotates very slowly. For these reasons, temperatures on the surface of Mercury vary widely. In direct sunlight, the surface can be as hot as 427 C (801 F). On the dark side, or in the shadows inside craters, the surface can be as cold as -183 C (-297 F)! Although most of Mercury is extremely dry, scientists think Mercury is covered with craters, like Earths Moon. MESSENGER has taken extremely detailed pictures of the planets surface. there may be a small amount of water in the form of ice at the poles of Mercury, in areas that never receive direct sunlight. Figure 1.3 shows a diagram of Mercurys interior. Mercury is one of the densest planets. Its relatively large, liquid core, made mostly of melted iron, takes up about 42% of the planets volume.
Question: the core of mercury is made mostly of melted
[A]: iron

[Q]: Context: September 1939. Mrs. Kay Miniver (Greer Garson) and her family live a comfortable life at a house called 'Starlings' in Belham, a fictional village outside London, England. The house has a large garden, with a private landing stage on the River Thames at which is moored a motorboat belonging to her devoted husband Clem (Walter Pidgeon), a successful architect. They have three children: the youngsters Toby and Judy (Christopher Severn and Clare Sandars) and an older son Vin (Richard Ney) at university. They have live-in staff: Gladys the housemaid (Brenda Forbes) and Ada the cook (Marie De Becker).As World War II looms, Vin comes down from university and meets Carol Beldon (Teresa Wright), granddaughter of Lady Beldon (Dame May Whitty) from nearby Beldon Hall. Despite initial disagreements (mainly contrasting Vin's idealistic attitude to class differences with Carol's practical altruism) they fall in love. Vin proposes to Carol in front of his family at home after his younger brother prods him to give a less romantic but more honest proposal.Several months later, as the war comes closer to home with the bombing of Great Brittan, Vin feels he must "do his bit" and enlists in the Royal Air Force, qualifying as a fighter pilot. He is posted to a base near to his parents' home and is able to signal his safe return from operations to his parents by cutting his engines briefly as he flies over the house. Together with other boat owners, Clem volunteers to take his motorboat to assist in the May-June 1940 Dunkirk evacuation.Early one morning, Kay unable to sleep as Clem is still away, wanders down to the landing stage. She is startled to discover a wounded German pilot (Helmut Dantine) hiding in her garden and he holds her at gunpoint. Demanding food and a coat, the pilot maniacally asserts that the Third Reich will mercilessly overcome its enemies. She feeds him, calmly disarms him and then calls the police. Soon after, Clem returns home, exhausted, from Dunkirk.Lady Beldon visits Kay to try and convince her to talk Vin out of marrying Carol on account of her granddaughter's comparative youth. Lady Beldon is unsuccessful and admits defeat when Kay reminds her that she, too, was young when she married her late husband. Lady Beldon concedes defeat and realises that she would be foolish to try and stop the marriage. Vin and Carol are married; Carol has now also become Mrs Miniver, and they return from their honeymoon in Scotland. A key theme is that she knows he is likely to be killed in action, but the short love will fill her life. Later, Kay and her family take refuge in their Anderson shelter in the garden during an air raid, and attempt to keep their minds off the frightening bombing by reading Alice's Adventures in Wonderland, which Clem refers to as a "lovely story" as they barely survive a bomb destroys parts of the house. They take the damage with nonchalance.At the annual village flower show, Lady Beldon silently disregards the judges' decision that her rose is the winner, instead announcing the entry of the local stationmaster, Mr. Ballard (Henry Travers), named the "Mrs. Miniver" rose, as the winner, with her own rose taking second prize. As air raid sirens sound and the villagers take refuge in the cellars of Beldon Hall, Kay and Carol drive Vin to join his squadron. On their journey home they witness fighter planes in a 'dogfight'. For safety, Kay stops the car and they see the German plane crash. Kay realises Carol has been wounded by shots from the plane and takes her back to 'Starlings'. She dies a few minutes after they reach home. Kay is devastated. When Vin returns from battle, he already knows the terrible news. Unexpectedly he is the survivor, and she the one who gives her life for England.The villagers assemble at the badly damaged church where their vicar (Henry Wilcoxon) affirms their determination in a powerful sermon:"We in this quiet corner of England have suffered the loss of friends very dear to us, some
Question: Who enlists in the Royal Air Force?
[A]: vin

[Q]: Context: The Sun is Earths main source of energy. The Sun gives us both light and heat. The Sun changes hydrogen into helium through nuclear fusion. This releases huge amounts of energy. The energy travels to the Earth mostly as visible light. The energy is carried through the empty space by radiation. We can use sunlight as an energy resource, called solar energy (Figure 5.7). Solar energy has been used on a small scale for hundreds of years. Today we are using solar energy for more of our power demands. Solar power plants are being built in many locations around the world. In the United States, the southwestern deserts are well suited for solar plants. Sunlight is turned into electricity at a solar power plant. These power plants use a large group of mirrors to focus sunlight on one place. This place is called a receiver (Figure 5.8). At the receiver, a liquid such as oil or water is heated to a high temperature. The liquid transfers its heat by conduction. In conduction, energy moves between two objects that are in contact. The higher temperature object transfers heat to the lower temperature object. For example, when you heat a pot of water on a stove top, energy moves from the pot to its metal handle by conduction. At a solar power plant, the energy conducted by the heated liquid is used to make electricity. Solar energy is used to heat homes and water, and to make electricity. Scientists and engineers have many ways to get energy from the Sun (Figure 5.9). One is by using solar cells. Solar cells are devices that turn sunlight directly into electricity. Lots of solar cells make up an individual solar panel. You may have seen solar panels on roof tops. The Suns heat can also be trapped in your home by using south facing windows and good insulation. Solar energy has many benefits. It does not produce any pollution. There is plenty of it available, much more than we could possibly use. But solar energy has problems. The Sun doesnt shine at night. A special battery is needed to store extra energy during the day for use at night. The technology for most uses of solar energy is still expensive. Until solar technology becomes more affordable, most people will prefer to get their energy from other sources. Moving water has energy (Figure 5.10). That energy is used to make electricity. Hydroelectric power harnesses the energy of water moving down a stream. Hydropower is the most widely used form of renewable energy in the world. This abundant energy source provides almost one fifth of the worlds electricity. The energy of waves and tides can also be used to produce water power. At this time, wave and tidal power are rare. To harness water power, a stream must be dammed. Narrow valleys are the best for dams. While sitting in the reservoir behind the dam, the water has potential energy. Water is allowed to flow downhill into a large turbine. While flowing downhill, the water has kinetic energy. Kinetic energy makes the turbine spin. The turbine is connected to a generator, which makes electricity. Many of the suitable streams in the United States have been developed for hydroelectric power. Many streams worldwide also have hydroelectric plants. Hydropower is a major source of Californias electricity. It accounts for about 14.5 percent of the total. Most of Californias nearly 400 hydroelectric power plants are located in the Sierra Nevada mountains. Water power does not burn a fuel. So it causes less pollution than many other kinds of energy. Water power is also a renewable resource. Water keeps flowing downhill. Although we use some of the energy from this movement, we are not using up the water. Water power does have problems. A large dam stops a streams flow, which floods the land upstream. A beautiful location may be lost. People may be displaced. The dams and turbines also change the downstream environment. Fish and other living things may not be able to survive. Dams slow the release of silt. Downstream deltas retreat and beaches may be starved of sand. Seaside cities may become exposed to storms and
Question: When energy moves through material, but the material itself does not move, this is
[A]:
conduction