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: Blood delivers oxygen in the body. Proteins and acids are broken down in the liver. The liver releases waste in the form of urea. The blood carries the urea and carbon dioxide to the kidneys. The kidneys strain the urea and salts needed from the blood. The carbon dioxide by product is transported back to the lungs. Carbon dioxide is exhaled by the lungs. 
Example Output: oxygen ,proteins and acids ,waste ; urea ,carbon dioxide ,salt 

Example Input: Get the ice tray. Remove any ice cubes currently in the tray. Fill the tray with cold water. Ensure the tray is evenly filled to an appropriate level. Open the freezer. Place the tray in the freezer. Close the freezer door. Wait. 
Example Output: ice tray ; tray ,ice cubes ,cold water 

Example Input: People breathe and expel carbon dioxide. Engines produce carbon dioxide. Living things produce waste. Waste decomposes. Decomposition produces methane. Water evaporates. Water vapor joins the atmosphere. Carbon dioxide, water vapor and methane are greenhouse gases. 
Example Output:
carbon dioxide ,methane ,water ,water vapor ,greenhouse gases