In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 

Q: The air is cold. Water is in the air. The water forms tiny ice crystals. The ice crystals collide with each other. The ice crystals stick to each other. The ice crystals get bigger as more of them stick together. The ice crystals get too heavy to be in the air. The ice crystals become snowflakes. The snow flakes fall to the ground as snow. 

A: water ,ice crystals ,snow flakes; snowflakes; snow 
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Q: The cornea and lens refract light into a small image. Shine it on the retina. The retina's rods and cones convert it to electrical pulses. The optic nerve carries electrical pulses through the optic canal. Nerve fibers end in the lateral geniculate nucleus and the visual cortex. 

A: light ,small image ,retina's rods and cones ,electrical pulses 
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Q: You find an empty ice cube tray. You fill the tray with warm water. You carefully place the tray on an even surface in a freezer that is at least 32 degree Farhenheit, the freezing point of water. The water begins to get colder until it starts to freeze solid. The water expands as it freezes, one of the few liquids that has greater volume as a solid. Because you used warm water, the gasses in the water had evaporated out, so you will have nice clear ice cubes without cracks from the trapped gasses. 

A:
warm water ,ice cubes 
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