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: Did you ever make a secret code? One way to make a code is to represent each letter of the alphabet by a different number. Then you can send a coded message by writing words as strings of digits. This is similar to how information is encoded using an electric current. The voltage of the current is changed rapidly and repeatedly to encode a message, called an electronic signal. There are two different types of electronic signals: analog signals and digital signals. Both are illustrated in Figure 23.20. A digital signal consists of pulses of voltage, created by repeatedly switching the current off and on. This type of signal encodes information as a string of 0s (current off) and 1s (current on). This is called a binary ("two-digit") code. DVDs, for example, encode sounds and pictures as digital signals. An analog signal consists of continuously changing voltage in a circuit. For example, microphones encode sounds as analog signals. Electronic components are the parts used in electronic devices such as computers. The components transmit and change electric current. They are made of materials called semiconductors. A semiconductor is a solid crystalusually consisting mainly of siliconthat can conduct current better than an electric insulator but not as well as an electric conductor. Very small amounts of other elements, such as boron or phosphorus, are added to the silicon so it can conduct current. A semiconductor is illustrated in Figure 23.21. There are two different types of semiconductors: n-type and p-type. An n-type semiconductor consists of silicon and an element such as phosphorus that gives the silicon crystal extra electrons. An n-type semiconductor is like the negative terminal in a chemical cell. A p-type semiconductor consists of silicon and an element such as boron that gives the silicon positively charged holes where electrons are missing. A p-type semiconductor is like the positive terminal in a chemical cell. Electronic components contain many semiconductors. Types of components include diodes, transistors, and inte- grated circuits. Each type is described in Table 23.2. Electronic Component Diode Transistor Integrated Circuit (Microchip) Description A diode consists of a p-type and an n-type semicon- ductor placed side by side. When a diode is connected by leads to a source of voltage, electrons flow from the n-type to the p-type semiconductor. This is the only direction that electrons can flow in a diode. This makes a diode useful for changing alternating current to direct current. A transistor consists of three semiconductors, either p- n-p or n-p-n. Current cant flow through a transistor unless a small amount of current is applied to the center semiconductor (through the base). Then a much larger current can flow through the transistor from end to end (from collector to emitter). This means that a transmitter can be used as a switch, with pulses of a small current turning a larger current on and off. A transistor can also be used to increase the amount of current flowing through a circuit. You can learn more about transistors and how they work at this URL: http An integrated circuitalso called a microchipis a tiny, flat piece of silicon that consists of layers of elec- tronic components such as transistors. An integrated circuit as small as a fingernail can contain millions of electronic components. Current flows extremely rapidly in an integrated circuit because it doesnt have far to travel. You can learn how microprocessors are made at this URL: Many of the devices you commonly use are electronic. Electronic devices include computers, mobile phones, TV remotes, DVD and CD players, game systems, MP3 players, and digital cameras. All of these devices use electric current to encode, analyze, or transmit information. Consider the computer as an example of an electronic device. A computer contains microchips with millions of tiny electronic components. Information is encoded as 0s and 1s and transmitted as electrical pulses. One digit (either 0 or 1) is called a bit, which stands for "binary digit." Each group of eight digits is called a byte. A gigabyte is a billion bytes that
Question: The type of electronic component that can be used to increase the amount of current flowing through a circuit is a

Ex Output:
transistor.

Ex Input:
Context: 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,
Question: What kind of class is Hiccup attending?

Ex Output:
dragon training

Ex Input:
Context: A 29-year-old man with a history of elevated creatine kinase and necrotizing myopathy was reviewed. Prominent red cell acanthocytosis in association with reduced Kell antigen expression was present, findings consistent with the McLeod syndrome. Investigation of the patient's XK gene revealed a novel TGG- to-TAG transition at position 1023 in exon 3. This point mutation creates an in-frame stop codon (W314X), and predicts a truncated XK protein of 313 amino acids, compared with 444 amino acids in the normal XK protein. The mutation was not identified in the patient's mother or sister indicating that this mutation was spontaneous.
Question: Mutation of which gene is associated with McLeod syndrome?

Ex Output:
xk