instruction:
Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
question:
All rocks on Earth change, but these changes usually happen very slowly. Some changes happen below Earths surface. Some changes happen above ground. These changes are all part of the rock cycle. The rock cycle describes each of the main types of rocks, how they form and how they change. Figure 4.1 shows how the three main rock types are related to each other. The arrows within the circle show how one type of rock may change to rock of another type. For example, igneous rock may break down into small pieces of sediment and become sedimentary rock. Igneous rock may be buried within the Earth and become metamorphic rock. Igneous rock may also change back to molten material and re-cool into a new igneous rock. Rocks are made of minerals. The minerals may be so tiny that you can only see them with a microscope. The minerals may be really large. A rock may be made of only one type of mineral. More often rocks are made of a mixture of different minerals. Rocks are named for the combinations of minerals they are made of and the ways those minerals came together. Remember that different minerals form under different environmental conditions. So the minerals in a rock contain clues about the conditions in which the rock formed (Figure 4.2). Geologists group rocks based on how they were formed. The three main kinds of rocks are: 1. Igneous rocks form when magma cools below Earths surface or lava cools at the surface (Figure 4.3). 2. Sedimentary rocks form when sediments are compacted and cemented together (Figure 4.4). These sediments may be gravel, sand, silt or clay. Sedimentary rocks often have pieces of other rocks in them. Some sedimentary rocks form the solid minerals left behind after a liquid evaporates. 3. Metamorphic rocks form when an existing rock is changed by heat or pressure. The minerals in the rock change but do not melt (Figure 4.5). The rock experiences these changes within the Earth. Rocks can be changed from one type to another, and the rock cycle describes how this happens. Any type of rock can change and become a new type of rock. Magma can cool and crystallize. Existing rocks can be weathered and eroded to form sediments. Rock can change by heat or pressure deep in Earths crust. There are three main processes that can change rock: Cooling and forming crystals. Deep within the Earth, temperatures can get hot enough to melt rock. This molten material is called magma. As it cools, crystals grow, forming an igneous rock. The crystals will grow larger if the magma cools slowly, as it does if it remains deep within the Earth. If the magma cools quickly, the crystals will be very small. Weathering and erosion. Water, wind, ice, and even plants and animals all act to wear down rocks. Over time they can break larger rocks into smaller pieces called sediments. Moving water, wind, and glaciers then carry these pieces from one place to another. The sediments are eventually dropped, or deposited, somewhere. The sediments may then be compacted and cemented together. This forms a sedimentary rock. This whole process can take hundreds or thousands of years. Metamorphism. This long word means to change form. A rock undergoes metamorphism if it is exposed to extreme heat and pressure within the crust. With metamorphism, the rock does not melt all the way. The rock changes due to heat and pressure. A metamorphic rock may have a new mineral composition and/or texture. An interactive rock cycle diagram can be found here: The rock cycle really has no beginning or end. It just continues. The processes involved in the rock cycle take place over hundreds, thousands, or even millions of years. Even though for us rocks are solid and unchanging, they slowly change all the time.
answer:
The process in which sedimentary rocks form begins with


question:
Decameron Nights is a 1953 anthology Technicolor film based on three tales from The Decameron by Giovanni Boccaccio, specifically the ninth and tenth tales of the second day and the ninth tale of the third.
answer:
The Decameron Nights is based upon what?


question:
A Viking boy called Hiccup (voice: Jay Baruchel) introduces his village of Berk ("it's been here for seven generations, but every single building is new"). The village is attacked by dragons, who steal food (mostly sheep) and set things on fire (hence all the new buildings). The villagers grab weapons and try to fight the dragons off. Despite being told by every adult in sight to go indoors, Hiccup hauls out a bolas-shooting cannon he made himself and shoots a dragon out of the night sky. (As assistant to the village blacksmith, Gobber (voice: Craig Ferguson), Hiccup has access to tools and materials and knows how to use them.) The dragon lands in the woods some distance form the village and no one believes that he hit anything, so it's the next day before Hiccup can go looking for it. It turns out to be a rare and deadly Night Fury, but Hiccup can't make himself kill it. Instead he releases it -- whereupon it also refrains from killing Hiccup -- and it flies off through the trees.Hiccup discovers that the dragon (which he eventually calls Toothless because of its retractable teeth) has holed up in a steep-sided valley because it can no longer fly more than a few feet at a time. While sketching the dragon, Hiccup realizes that it's missing a tail fin. He makes a prosthetic tail fin out of leather. The new fin helps, but Toothless can't control it and inadvertently takes Hiccup for a ride, giving him a clear idea of what's needed to help the dragon fly right. In a series of workshop and test flight scenes, Hiccup builds and perfects a saddle, a control mechanism for the tail fin, and a safety harness.Meanwhile, Hiccup's father Stoick (voice: Gerard Butler) has signed him up for dragon training with Gobber, which is very different from the training he's already doing with Toothless: he's going to learn to fight dragons. At first, he's the worst student in the class. Since Hiccup has always been an accident-prone klutz, this comes as no surprise to his classmates Astrid (voice: America Ferrera), Snotlout (voice: Jonah Hill), Fishlegs (voice: Christopher Mintz-Plasse), Ruffnut (voice: Kristen Wiig), and her twin brother Tuffnut (voice: T.J. Miller). (Hiccup's a little sweet on Astrid.) Before long, Hiccup is able to use some things he's learned while working with Toothless to soothe and manage the school's practice dragons. (It turns out dragons are just big kitty-cats: they like to be petted, there's a kind of grass that's like cat-nip to them, and they love fish (but hate eels).) When Stoick returns from a failed search for the fabled nest of the dragons, he's surprised but thrilled to hear that his son is doing brilliantly at dragon training. He gives Hiccup a horned helmet made from one of his dead mother's breastplates. But Hiccup, as usual, is unable to get around his father's expectations and speak frankly, so he can't explain that his success at dragon school is unlikely to lead to the slaying of any dragons.When Hiccup subdues a practice dragon, unintentionally earning the privilege of killing it before the entire village, he's horrified and decides to flee with Toothless. However Astrid, having noticed Hiccup's frequent disappearances and secretive behavior, is suspicious. She follows him to the hidden valley and sees Toothless. Unable to explain his relationship with the dragon, Hiccup takes her flying, and she's captivated. But they get caught up in a flock of dragons returning to their nest carrying food. The dragons fly inside a mountainous island and drop the food into a pit, which turns out to contain a huge, terrifying, and very hungry dragon that eats the smaller ones if they don't bring it enough food. Hiccup and Astrid and shocked to realize that the dragons have been stealing their sheep to keep from being eaten themselves. When they get home,
answer:

What do the Vikings expel most of?