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: 1836 Komarov, provisional designation 1971 OT, is a main-belt asteroid discovered on 26 July 1971 by Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnyj. 
 Question: Who discovered 1836 Komarov?

Ex Output:
nikolai chernykh


Ex Input:
Context: Weathering changes solid rock into sediments. Sediments are different sizes of rock particles. Boulders are sedi- ments; so is gravel. At the other end, silt and clay are also sediments. Weathering causes rocks at the Earths surface to change form. The new minerals that form are stable at the Earths surface. It takes a long time for a rock or mountain to weather. But a road can do so much more quickly. If you live in a part of the world that has cold winters, you may only have to wait one year to see a new road start to weather (Figure Mechanical weathering breaks rock into smaller pieces. These smaller pieces are just like the bigger rock; they are just smaller! The rock has broken without changing its composition. The smaller pieces have the same minerals in the same proportions. You could use the expression a chip off the old block to describe mechanical weathering! The main agents of mechanical weathering are water, ice, and wind. Rocks can break apart into smaller pieces in many ways. Ice wedging is common where water goes above and below its freezing point (Figure 9.2). This can happen in winter in the mid-latitudes or in colder climates in summer. Ice wedging is common in mountainous regions. This is how ice wedging works. When liquid water changes into solid ice, it increases in volume. You see this when you fill an ice cube tray with water and put it in the freezer. The ice cubes go to a higher level in the tray than the water. You also may have seen this if you put a can of soda into the freezer so that it cools down quickly. If you leave the can in the freezer too long, the liquid expands so much that it bends or pops the can. (For the record, water is very unusual. Most substances get smaller when they change from a liquid to a solid.) Abrasion is another type of mechanical weathering. With abrasion, one rock bumps against another rock. Gravity causes abrasion as a rock tumbles down a slope. Moving water causes abrasion it moves rocks so that they bump against one another (Figure 9.3). Strong winds cause abrasion by blasting sand against rock surfaces. Finally, the ice in glaciers cause abrasion. Pieces of rock embedded in ice at the bottom of a glacier scrape against the rock below. If you have ever collected beach glass or pebbles from a stream, you have witnessed the work of abrasion. Sometimes biological elements cause mechanical weathering. This can happen slowly. A plants roots grow into a crack in rock. As the roots grow larger, they wedge open the crack. Burrowing animals can also cause weathering. By digging for food or creating a hole to live in the animal may break apart rock. Today, human beings do a lot of mechanical weathering whenever we dig or blast into rock. This is common when we build homes, roads, and subways, or quarry stone for construction or other uses. Mechanical weathering increases the rate of chemical weathering. As rock breaks into smaller pieces, the surface area of the pieces increases. With more surfaces exposed, there are more places for chemical weathering to occur. Lets say you wanted to make some hot chocolate on a cold day. It would be hard to get a big chunk of chocolate to dissolve in your milk or hot water. Maybe you could make hot chocolate from some smaller pieces like chocolate chips, but it is much easier to add a powder to your milk. This is because the smaller the pieces are, the more surface area they have. Smaller pieces dissolve more easily. Chemical weathering is different than mechanical weathering. The minerals in the rock change. The rock changes composition and becomes a different type of rock. Most minerals form at high pressure or high temperatures deep within Earth. But at Earths surface, temperatures and pressures are much lower. Minerals that were stable deeper in the crust are not stable at the surface. Thats why chemical weathering happens. Minerals that formed at higher temperature and pressure change into minerals that are stable at the surface. Chemical weathering is important. It 
 Question: weathering process that occurs when rocks and rock particles scrape other rocks

Ex Output:
abrasion


Ex Input:
Context: Jack Elgin is the European editor of The Economist, which is based in London, England. Jack has a wife named Maria and three kids named Joanne, Julia, and Andrew. Jack subtly changes the family vacation from a lazy week of Mediterranean fun and sun in Corfu, Greece, to a tour of India, because of a story he has to cover. Maria is not as impressed by this as the kids are. Jack himself envisioned a chance to simultaneously work an easy reporting assignment and spend a little quality time with his family. But on the way to India, the airplane, a 747 owned by AM Air, an American airline, makes an unscheduled stopover in Limassol Cyprus, because of a mechanical problem. After a while of waiting inside the Limassol airport, everyone gets back on the plane -- which is then hijacked by a group of terrorists known as the August 15th Movement, led by a Serbian man named Ivanic Loyvek and his right-hand man Karadan Maldic. The terrorists take a silver briefcase from an diplomatic courier, an older man, and it appears to be an important object of their hijack. And they are demanding $50,000,000 from the US State Department in one hour, or everyone on the airplane will die.The demand is met, and Loyvek and Maldic start releasing the women and children, with the men to go last. But as soon as a front passenger door is opened, the local police begins shooting. Inside the plane, the owner of the briefcase retrieves it, only to be killed the terrorists, who take it again.The flight attendants frantically open the rest of the airplane's doors and start getting passengers out, but the terrorists start killing passengers, leading to an explosion. Maria, Joanne, and Julia get out of the airplane, and then Jack, holding Andrew, gets out -- only to watch Maria, Joanne, and Julia get shot by the terrorists. Jack tries to hide Andrew's face so he can't see. Maria and Joanne are killed, but Julia burns to death while crying for help.Jack and Andrew survive. 15 passengers die, and Loyvek and Maldic, the surviving terrorists, escape, knowing that they now have the $50,000,000. Back in London, a devastated Jack is told that the terrorists were captured, but they were released and deported secretly, with no charges and no arrest, the result of some awfully compromised politics. Jack is understandably enraged that Loyvek and Maldic got off scot-free. While helping Andrew cope, Jack tries all the legal ways to ensure justice for his family, but to no avail.Jack even pays a visit to Henry Davidson, a CIA agent who works at the American Embassy in London. Davidson tells Jack that there's little that can be done. The American and British governments are completely impotent when it comes to going after Loyvek and Maldic. Jack decides he has no choice in the matter but to seek revenge. With the help of his ex-intelligence operative friend Kate Stockton, who is well-schooled in the finer points of international intelligence, Jack becomes a one-man anti-terrorist squadron, searching for Loyvek and Maldich. He finds a warehouse they apparently are using as a headquarters. Breaking in, he finds some papers which he takes, and some weapons. The terrorists return, find a flashlight Jack was using, and begin searching the warehouse. Jack returns upstairs, retrieves a machine pistol and loads it with a magazine. He kills three terrorists before escaping.He later breaks into the home of a friend at MI6 and steals a Walther PPK pistol from his home. He shows up at a theatre and makes a scene at the bar, to be sure he is noticed by the bartender. He then follows one of the terrorists in his taxicab, killing him with that weapon. He returns to the theatre and makes a point of apologizing to the bartender. The next day he goes pheasant hunting with his MI6 contact in case he is tested for gunpowder residue.Dogging Jack's trail is FBI agent Jules Bernard, who's cooperating with Scotland Yard on anti-terrorist activities, and who suspects 
 Question: Who does Jack visit?

Ex Output:

henry davidson