Task: Question Generation
Input (English): Background Paragraph: Liquid water is a fluid. The hydrogen bonds in liquid water constantly break and reform as the water molecules tumble past one another. As water cools, its molecular motion slows and the molecules move gradually closer to one another. The density of any liquid increases as its temperature decreases. For most liquids, this continues as the liquid freezes and the solid state is denser than the liquid state. However, water behaves differently. It actually reaches its highest density at about 4°C. 
Story: Joe is at a party and carrying around a can of beer that he has had in his hand for awhile. He bumps into Sally, and they begin chatting. During their conversation, Sally notices the beer in Joe's hand, and remarks that a beer sounds like a good idea. She heads over to the refrigerator and grabs a nice cold one and pops it open. She takes a sip while the two continue their chat.
Output (English): The molecules in whose can of beer are moving slower?