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. 

Ex Input:
Coal is burned in a boiler. Steam is produced under pressure. Flows into a turbine. The turbine spins. Creates electricity. 

Ex Output:
coal ,steam ,turbine ,electricity 


Ex 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. 

Ex Output:
carbon dioxide ,methane ,water ,water vapor ,greenhouse gases 


Ex Input:
There is a fetus in the womb. They are born and are a baby. The baby grows into a child. Puberty turns the child into an adolescent. The adolescent becomes an adult. An adult becomes an elderly person. The elderly person dies. 

Ex Output:

fetus ,baby ,child ,adolescent ,adult ,elderly person