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: Elements form compounds when they combine chemically. Their atoms join together to form molecules, crystals, or other structures. The atoms are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions. It occurs when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom. You can learn more about chemical bonds in this video: MEDIA Click image to the left or use the URL below. URL: Look at the example of water in Figure 7.1. A water molecule consists of two atoms of hydrogen and one atom of oxygen. Each hydrogen atom has just one electron. The oxygen atom has six valence electrons. In a water molecule, two hydrogen atoms share their two electrons with the six valence electrons of one oxygen atom. By sharing electrons, each atom has electrons available to fill its sole or outer energy level. This gives it a more stable arrangement of electrons that takes less energy to maintain. Water (H2 O) is an example of a chemical compound. Water molecules always consist of two atoms of hydrogen and one atom of oxygen. Like water, all other chemical compounds consist of a fixed ratio of elements. It doesnt matter how much or how little of a compound there is. It always has the same composition. Elements are represented by chemical symbols. Examples are H for hydrogen and O for oxygen. Compounds are represented by chemical formulas. Youve already seen the chemical formula for water. Its H2 O. The subscript 2 after the H shows that there are two atoms of hydrogen in a molecule of water. The O for oxygen has no subscript. When there is just one atom of an element in a molecule, no subscript is used. Table 7.1 shows some other examples of compounds and their chemical formulas. Name of Compound Electron Dot Diagram Numbers of Atoms Chemical Formula Name of Compound Hydrogen chloride Electron Dot Diagram Numbers of Atoms H=1 Cl = 1 Chemical Formula HCl Methane C=1 H=4 CH4 Hydrogen peroxide H=2 O=2 H2 O2 Carbon dioxide C=1 O=2 CO2 Problem Solving Problem: A molecule of ammonia consists of one atom of nitrogen (N) and three atoms of hydrogen (H). What is its chemical formula? Solution: The chemical formula is NH3 . You Try It! Problem: A molecule of nitrogen dioxide consists of one atom of nitrogen (N) and two atoms of oxygen (O). What is its chemical formula? The same elements may combine in different ratios. If they do, they form different compounds. Figure 7.2 shows some examples. Both water (H2 O) and hydrogen peroxide (H2 O2 ) consist of hydrogen and oxygen. However, they have different ratios of the two elements. As a result, water and hydrogen peroxide are different compounds with different properties. If youve ever used hydrogen peroxide to disinfect a cut, then you know that it is very different from water! Both carbon dioxide (CO2 ) and carbon monoxide (CO) consist of carbon and oxygen, but in different ratios. How do their properties differ? There are different types of compounds. They differ in the nature of the bonds that hold their atoms together. The type of bonds in a compound determines many of its properties. Three types of bonds are ionic, covalent, and metallic bonds. You will read about these three types in later lessons. You can also learn more about them by watching this video: (7:18). MEDIA Click image to the left or use the URL below. URL: Chocolate: Its been revered for millennia by cultures throughout the world. But while its easy to appreciate all of its delicious forms, creating this confection is a complex culinary feat. Local chocolate makers explain the elaborate engineering and chemistry behind this tasty treat. And learn why its actually good for your health! For more information on the science of chocolate, see [Link] . MEDIA Click image to the left or use the URL below. URL: 
 Question: force of attraction between atoms or ions that share or transfer electrons
answer:
chemical bond


question:
Context: Modeled after US hot website.com, group buying websites are now popular in China. These websites use the power of group buying to get competitive discounts for a daily deal on some best stuff to do, see, eat and buy in the cities across China. Discounts are available within just one click. Zhao lei, a software engineer in Beijing, loves the one-hour lunch break at noon,as it is the best time for him to check "today's special" at his favorite group buying websites . Sometimes he searches for great deals at directory sites devoted to the new shopping space. Zhao spends around 800 yuan($117.65) on group buying every month, mostly to buy food coupons for eating at some nice restaurants and occasionally to find something fun to do. " I love group buying. In addition to the competitive discounts it offers, it helps me get something fun, exciting and new, and such surprises give me a reason to try something new," he said. When he finds a really good bargain, he will send the link to friends or colleagues through MSN,QQ, or e-mail, or share the information at some social networking websites. In doing so, he often gets a certain cut off the price. At some sites, buyers are invited to leave notes about what they want to buy and the website will consider it if similar applications reach a certain number. That is how Zuo got her digital camera after waiting for two months. "It is cool. I want to buy a new digitgal camera for my trip to Switzerland this winter, but I never expected such cheap prices!" Zuo said. 
 Question: What is the passage mainly about?
answer:
group buying


question:
Context: The police must investigate a series of robberies along a strip of land in the city. The new mayor of the city (Kenneth Mars) assigns Captain Harris (G.W. Bailey) and Lt. Proctor (Lance Kinsey) to the case, but while on stakeout the Wilson gang manages to slip through their fingers.The Mayor wants Harris and Proctor to work with Police Academy head Commandant Lassard (George Gaynes) on apprehending the gang. Lassard assembles a seven-man team consisting of Hightower (Bubba Smith), Tackleberry (David Graf), Jones (Michael Winslow), Hooks (Marion Ramsey), Callahan (Leslie Easterbrook), Fackler (Bruce Mahler), and Lassard's nephew, Nick (Matt McCoy) who transfers from Miami (in the previous film Police Acdemy 5) to the city to remain close to his friends and dull-witted uncle.After distributing flyers as to the information of the Wilson gang and getting nowhere, Nick McCoy stumbles upon a paper heading of an antique diamond heading to a museum, and gets an idea to use it as bait: however the robbers nab the diamond anyway by cutting a hole in the truck and escaping through the sewer system. McCoy then decides to go undercover to get information regarding a possible hideout, but Harris decides to go undercover to get a confession.It turns out that Harris goes undercover as a window washer at a tall building, for which he has a fear of heights, and gets a confession of himself on tape after his loyal but numb-skull lacky, Proctor, accidentally knocks him over the balcony.It is revealed here that the robberies are committed by a group of three dim-witted criminals who do not seem to be able to do this on their own, and it is revealed they are being guided by a literally shadow figure known as the "Mastermind", who speaks to the three behind a wall of glass and uses a voice distortion device. He devises a plan to get the cops out of the way.Commandant Lassard and his men are later suspended after stolen jewellery from the last robbery is planted in Lassard's locker, pending an investigation. The misfit cops decide to clear Lassard's name by nabbing the gang and the ringleader. Accessing data files from a computer, McCoy deduces that the robberies are occurring along a bus route, thus intentionally lowering property values in that part of the city. They also learn that someone must be 'leaking' information to the bad guys, which is why they are always one step ahead of the Police Academy.The Police Academy force finds and does battle with the Wilson gang, while Nick chases the leader. A pursuit follows, which leads to Commissioner Hurst's (George Robertson) office. It is revealed that the Mayor is the "Mastermind" and that Captain Harris has been unwittingly leaking information during his daily meetings with the Mayor. Hurst apologizes and reinstates the force, and a plaque is given to honor the officers' bravery the next day.As the movie closes, Harris is sitting in a chair when a string tying the balloon float is cut, lifting his chair and floating him up into the air as he shouts Proctor's name. 
 Question: What does Nick get an idea to use the diamond as?
answer:

bait