instruction:
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. 
question:
Waste builds up in the blood. Blood enters the kidney. Blood passes through nephrons in the kidney. Different kinds of waste are momentarily trapped in the kidney. Cleaned blood flows out of the kidney. Filtered waste accumulates in liquid form (urine). Urine flows out of the kidney into the bladder. 
answer:
waste ,blood ,cleaned blood ,filtered waste ,urine 


question:
Fuel produces heat. Water is boiled to make steam. Steam spins turbine. Generator is turned. Makes electricity. Electricity transfers to transformers. Produces the correct voltage. 
answer:
fuel ,heat ,water ,steam ,turbine ,generator ,electricity ,voltage 


question:
Several types of gases form in the atmosphere. May come from different sources. The gases remain trapped in the atmosphere. Through the suns light the gases hold in heat and energy. Trap them in our atmosphere. The earth may become warmer this way. 
answer:

several types of gases ,atmosphere ,earth ,heat ,energy 


