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.
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Question: Fluid. Waste enters the kidneys. A processing moment in the kidneys let waste and fluid pass. Prevents larger molecules to pass. Fluid goes back to the bloodstream. Bad waste is removed. The final product is turned into urine.

Answer: fluid ,waste;larger molecules;bad waste ,urine

Question: Dissolution of limestone forms caves. Rain gets carbon dioxide from the air. When rain goes into soil it creates an acid. The acid dissolves the limestone along cracks. Some will dissolve enough to form caves.

Answer: carbon dioxide ,rain ,acid ,limestone ,caves

Question: Greenhouse gases are released into the air by human activities. The earth changes energy from the sun into heat. Heat rises from the ground. Greenhouse gas molecules in the atmosphere prevent the heat from going into space. The temperature of the earth increases. The temperature continues to rise and melts the polar ice caps. The temperature rises even faster.

Answer:
greenhouse gas ,air ,earth ,energy from sun ,heat ,greenhouse gas molecules ,polar ice cap