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.

Example Input: Context: From the outside, the skin looks plain and simple, as you can see in Figure 16.5. But at a cellular level, theres nothing plain or simple about it. A single square inch of skin contains about 20 blood vessels, hundreds of sweat glands, and more than a thousand nerve endings. It also contains tens of thousands of pigment-producing cells. Clearly, there is much more to skin than meets the eye! For a dramatic introduction to the skin, watch this video: MEDIA Click image to the left or use the URL below. URL: The skin is only about 2 mm thick, or about as thick as the cover of a book. Although it is very thin, it consists of two distinct layers, called the epidermis and the dermis. You can see both layers and some of their structures in Figure 16.6. Refer to the figure as you read about the epidermis and dermis below. The epidermis is the outer layer of skin. It consists almost entirely of epithelial cells. There are no blood vessels, nerve endings, or glands in this skin layer. Nonetheless, this layer of skin is very active. It is constantly being renewed. How does this happen? 1. The cells at the bottom of the epidermis are always dividing by mitosis to form new cells. 2. The new cells gradually move up through the epidermis toward the surface of the body. As they move, they produce the tough, fibrous protein called keratin. 3. By the time the cells reach the surface, they have filled with keratin and died. On the surface, the dead cells form a protective, waterproof layer. 4. Dead cells are gradually shed from the surface of the epidermis. As they are shed, they are replaced by other dead cells that move up from below. The epidermis also contains cells called melanocytes. You can see a melanocyte in Figure 16.7. Melanocytes produce melanin. Melanin is a brown pigment that gives skin much of its color. Everyones skin has about the same number of melanocytes per square inch. However, the melanocytes of people with darker skin produce more melanin. The amount of melanin that is produced depends partly on your genes and partly on how much ultraviolet light strikes your skin. The more light you get, the more melanin your melanocytes produce. This explains why skin tans when its exposed to sunlight. The dermis is the inner layer of skin. It is made of tough connective tissue. The dermis is attached to the epidermis by fibers made of the protein collagen. The dermis is where most skin structures are located. Look again at Figure pain, pressure, and temperature. If you cut your skin and it bleeds, the cut has penetrated the dermis and damaged a blood vessel. The cut probably hurts as well because of the nerve endings in this skin layer. The dermis also contains hair follicles and two types of glands. You can see some of these structures in Figure 16.8. Hair follicles are structures where hairs originate. Each hair grows out of a follicle, passes up through the epidermis, and extends above the skin surface. Sebaceous glands are commonly called oil glands. They produce an oily substance called sebum. Sebum is secreted into hair follicles. Then it makes its way along the hair shaft to the surface of the skin. Sebum waterproofs the hair and skin and helps prevent them from drying out. Sweat glands produce the salty fluid known as sweat. Sweat contains excess water, salts, and other waste products. Each sweat gland has a duct that passes through the epidermis. Sweat travels from the gland through the duct and out through a pore on the surface of the skin. You couldnt survive without your skin. It has many important functions. In several ways, it helps maintain homeostasis. The main function of the skin is controlling what enters and leaves the body. It prevents the loss of too much water from the body. It also prevents bacteria and other microorganisms from entering the body. Melanin in the epidermis absorbs ultraviolet light. This prevents the light from reaching and damaging the dermis. The skin helps maintain a constant body temperature. It 
 Question: __oily substance secreted by glands in the skin
Example Output: sebum

Example Input: Context: Energy, or the ability to do work, can exist in many different forms. The photo in Figure 17.8 represents six of the eight different forms of energy that are described in this lesson. The guitarist gets the energy he needs to perform from chemical energy in food. He uses mechanical energy to pluck the strings of the guitar. The stage lights use electrical energy and give off both light energy and thermal energy, commonly called heat. The guitar also uses electrical energy, and it produces sound energy when the guitarist plucks the strings. For an introduction to all these forms of energy, go to this URL: . For an interactive animation about the different forms of energy, visit this URL: After you read below about different forms of energy, you can check your knowledge by doing the drag and drop quiz at this URL: . Mechanical energy is the energy of an object that is moving or has the potential to move. It is the sum of an objects kinetic and potential energy. In Figure 17.9, the basketball has mechanical energy because it is moving. The arrow in the same figure has mechanical energy because it has the potential to move due to the elasticity of the bow. What are some other examples of mechanical energy? Energy is stored in the bonds between atoms that make up compounds. This energy is called chemical energy, and it is a form of potential energy. If the bonds between atoms are broken, the energy is released and can do work. The wood in the fireplace in Figure 17.10 has chemical energy. The energy is released as thermal energy when the wood burns. People and many other living things meet their energy needs with chemical energy stored in food. When food molecules are broken down, the energy is released and may be used to do work. Electrons are negatively charged particles in atoms. Moving electrons have a form of kinetic energy called electrical energy. If youve ever experienced an electric outage, then you know how hard it is to get by without electrical energy. Most of the electrical energy we use is produced by power plants and arrives in our homes through wires. Two other sources of electrical energy are pictured in Figure 17.11. The nuclei of atoms are held together by powerful forces. This gives them a tremendous amount of stored energy, called nuclear energy. The energy can be released and used to do work. This happens in nuclear power plants when nuclei fission, or split apart. It also happens in the sun and other stars when nuclei fuse, or join together. Some of the suns energy travels to Earth, where it warms the planet and provides the energy for photosynthesis (see Figure The atoms that make up matter are in constant motion, so they have kinetic energy. All that motion gives matter thermal energy. Thermal energy is defined as the total kinetic energy of all the atoms that make up an object. It depends on how fast the atoms are moving and how many atoms the object has. Therefore, an object with more mass has greater thermal energy than an object with less mass, even if their individual atoms are moving at the same speed. You can see an example of this in Figure 17.13. Energy that the sun and other stars release into space is called electromagnetic energy. This form of energy travels through space as electrical and magnetic waves. Electromagnetic energy is commonly called light. It includes visible light, as well as radio waves, microwaves, and X rays (Figure 17.14). The drummer in Figure 17.15 is hitting the drumheads with drumsticks. This causes the drumheads to vibrate. The vibrations pass to surrounding air particles and then from one air particle to another in a wave of energy called sound energy. We hear sound when the sound waves reach our ears. Sound energy can travel through air, water, and other substances, but not through empty space. Thats because the energy needs particles of matter to pass it on. Energy often changes from one form to another. For example, the mechanical energy of a moving drumstick changes to sound energy when it strikes the drumhead and causes it to vibrate. Any 
 Question: energy of an object that is moving or has the potential to move
Example Output: mechanical energy

Example Input: Context: In the opening scene, private detective Sam Grunion (Groucho Marx) explains to the viewers that he has been searching for the extremely valuable Royal Romanoff diamonds for eleven years, and his investigation leads him to a troupe of struggling performers, led by Mike Johnson (Paul Valentine), who are trying to put on a musical revue called 'Love Happy'.Grunion notes that the impoverished young dancers would starve were it not for the sweet, silent Harpo (Harpo Marx), at Herbert & Herbert, a gourmet food shop that also trafficks in stolen diamonds. Harpo kindly helps ladies with their shopping bags, all the while pilfering their groceries and stuffing them in the pockets of his long trench coat. When the elegant Madame Egelichi (Ilona Massey) arrives, store manager Lefty Throckmorton (Melville Cooper) tells her that "the sardines" have come in. Harpo sneaks into the basement and watches as Lefty lovingly unpacks a sardine can marked with a Maltese cross, and swipes the can from Lefty's pocket, replacing it with an unmarked one. Madame Egelichi, who has gone through eight husbands in three months in her quest for the Romanoff diamonds, is furious when Lefty produces the wrong can. When Lefty remembers seeing Harpo in the basement, she orders him to call the police and offer a $1,000 reward for his capture.At the theater, meanwhile, unemployed entertainer Faustino the Great (Chico Marx) asks Mike for a job as a mind-reader, and when Faustino's clever improvisation stops the show's backer, Mr. Lyons (Leon Belasco), from repossessing the scenery, Mike gratefully hires him. Harpo, who is secretly in love with dancer Maggie Phillips (Vera-Ellen), Mike's girl friend, gives her the sardine can, and she says she will eat them tomorrow. A policeman sees Harpo inside the theater and brings him to Madame Egelichi, who turns Harpo over to her henchmen, Alphonse (Raymond Burr) and Hannibal (Bruce Gordon) Zoto. After three days of interrogation, Harpo still refuses to talk, and when he is left alone, he calls Faustino at the theater, using the bike horn he carries in his pocket to communicate. Madame Egelichi listens on the extension as Faustino declares that there are plenty of sardines at the theater, and she goes there at once.Meanwhile, Mike has just finished telling the troupe that they do not have enough money to open when Madame Egelichi arrives and offers to finance the show. Mike cancels his plans to take Maggie out for her birthday so that he and his new backer can discuss the arrangements. In the alley outside the theater, Harpo, having escaped from Madame Egelichi's suite, finds the diamonds in the sardine can which had been set out for a cat, and puts them in his pocket. When he finds Maggie crying in her dressing room, Harpo takes her to Central Park, where he plays the harp for her and gives her the diamonds as a birthday gift.On the opening night of the show, Grunion is visited by an agent of the Romanoff family, who threatens to kill him if he does not produce the diamonds in an hour. At the theater, Lefty and the Zoto brothers spy through a window as Maggie puts on the diamond necklace, but Mike asks her not to wear it, promising to buy her an engagement ring instead. As they kiss, Maggie removes the necklace and drops it on the piano strings. The curtain goes up, and when Harpo sees Lefty and the Zoto brothers menacing Maggie, he distracts them with a piece of costume jewelry and leads them up to the roof.Meanwhile, on stage, Faustino plays the piano, and when he strikes the keys forcefully, the diamond necklace flies into the air, drawing the attention of Madame Egelichi, who is watching from the audience. Faustino pockets the diamonds, then rushes to the roof to help Harpo. Madame Egelichi shows up with a gun and demands the necklace, but Faustino gives her the fake diamonds. After tying up Lefty and the Zotos and recovering the real diamonds, Harpo encounters Grunion, who has been hiding on the roof. Harpo drops the diamonds in Grunion 
 Question: Who plays piano on the stage?
Example Output:
faustino