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. 

Example Input: Water seeps into rocks. The water freezes and thaws. Cracks form in the rocks. Cracks also form when rocks heat up. The rocks slowly break down. 
Example Output: water ,rocks ,cracks 

Example Input: Air contains invisible moisture called water vapor. Excess water vapor is condensed out as water in the form of water droplets. Water droplets are carried up into the clouds. The clouds become heavy with water droplets. When the cloud is saturated. Rain will fall. 
Example Output: water vapor ,water droplets ,cloud ,rain 

Example Input: They take in fluids and liquids. They process the fluid. They take out the toxins. Produce urine. Urine is released. The nutrients are returned to the body. 
Example Output:
fluids and liquids ; fluid ; nutrients ,toxins ,urine