instruction:
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.
question:
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
answer:
abrasion


question:
Context: The Conquest of Melilla occurred in September 1497, when a fleet sent by the Duke of Medina Sidonia seized the north African city of Melilla., as continuation of Reconquest of Mauritania Tingitana During the 15th century the mediterranean cities of the Sultanate of Fez fell in decadence in opposition to cities located in the Atlantic facade, which concentrated most of the economic activity. By the end of the 15th century, the port of Melilla, that had been often disputed between the rulers of Fez and Tlemcen, was nearly abandoned. Plans for the conquest occurred as soon as the Fall of Granada in 1492. Spanish captains Lezcano and Lorenzo Zafra visited the coast of Northern Africa to identify possible locations for the Spanish to overtake, and Melilla was identified as a prime candidate. Melilla was, however, in the Portuguese zone of influence under the terms of the 1479 Treaty of Alcacovaz. At Tordesillas in 1494, King John II of Portugal, the Portuguese ruler agreed to make an exception and permitted the Spanish to attempt the conquest of Melilla. The duke sent Pedro Estopinan who conquered the city virtually without a fight in 1497, as internal conflicts had depleted it of troops, and its defenses were weakened. The Wattasid ruler Muhammad al-Shaykh sent a detachment of cavalrymen to retake control of the city, but they were repulsed by the guns of the Spanish ships. 
 Question: Which happened first, the fleet being sent by the Duke of Medina, or the Conquest of Melilla?
answer:
fleet sent by the duke


question:
Context: The Ehlers-Danlos syndromes (EDS) are a group of connective tissue disorders characterized by triad of joint hypermobility, skin extensibility, and tissue fragility. Ehlers-Danlos syndrome type IV places patients at risk for life-threatening, spontaneous, vascular or visceral rupture due to reduced or abnormal secretion of type III collagen. We present an adolescent male who was found to have a perisigmoid abscess with a fistula connecting to adjacent sigmoid colon secondary to undiagnosed EDS type IV. Conservative management with antibiotics and bowel rest was pursued to allow for elective resection for his acute complicated diverticulitis at a safer time. 
 Question: What tissue is most affected in Ehlers-Danlos syndromes?
answer:

connective tissue