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:
A nuclear reactor generates heat by nuclear fission. The heat created raises steam. The steam runs through turbines. The turbines generate electricity. The electricity leaves the station. 
answer:
heat ,steam ,electricity 


question:
Body temperature rises. The brain tells blood vessels to dilate. The sweat glands become active. Moisture is released from the pores. The moisture evaporates. The evaporation causes cooling. 
answer:
body ,brain ,blood vessels ,sweat glands ,moisture 


question:
Choose what you want to write your letter on. Think of what you want to say. Write some nice things!. Place the letter into an envelope. Put a stamp on the top right corner of the face of the envelope. Write the address of the recipient on the envelope. Put the envelope in your mailbox. Raise the flag on your mailbox, indicating to the mailman that you have outgoing mail. 
answer:

envelope ,flag on your mailbox ,letter ,nice things ,stamp