Final answer:
A slippery sheet is a potential characteristic of ice, which is created when the friction between a skate blade and the ice melts the surface slightly, creating a thin layer of water as a lubricant.
Step-by-step explanation:
A "slippery sheet" is a potential characteristic of ice. When a skater glides on ice, the friction between the skate blade and the ice causes the surface of the ice to melt slightly, creating a thin layer of water that acts as a lubricant. This allows the skater to glide smoothly over the ice.