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.

[Q]: 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
[A]: mechanical energy


[Q]: Context: Gerard Debreu (French: (db); 4 July 1921 -- 31 December 2004) was a French-born American economist and mathematician. 
 Question: What is the birth date of Gerard Debreu?
[A]: 4 july 1921


[Q]: Context: My friend had mentioned the other day that her father had a lot of children's toys he was looking to give away. She knew I have a three-year-old daughter so she thought of me first. I told her I would love it if I could get some nice things for my daughter, which I wouldn't otherwise have been able to afford. When I met her father, he began to explain he was too poor once and that he would hate to throw away things that can be very useful. Before he showed me what he was giving away, I thought the toys would be mostly lego's or things like that. When he was showing me around I saw a bed, a slide, a kitchen set and many other things that just blew my mind. He told me to write a list of everything my daughter could use and as my eyes were wide, he told me not to feel guilty. He said I was helping him by getting rid of the stuff. As I was looking around I did feel guilty, but I tried to remain more grateful than guilty. Every time I tried to thank him for giving me and my daughter all this wonderful stuff he would thank me right back. I wanted to believe that he was just thanking me so that I wouldn't feel so guilty but in reality I believe that he was as grateful as I was that these toys would be put to good use. In the eyes of charity, it makes sense to feel grateful, but guilt is just as normal. I know that we could have lived without a slide, which is why I do feel guilty, but I am grateful all the same because my daughter really does enjoy all these nice things! 
 Question: In the writer's opinion, the old man felt grateful because
[A]:
the toys would be put to good use