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: 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.
Example Output: envelope ,flag on your mailbox ,letter ,nice things ,stamp

Example Input: Trash is placed into a garbage container in the house. The trash is moved to a centralized container for the house. Trash is picked up by a sanitation company. The trash is combined in a large truck with trash from all around the city. The truck goes to the landfill. The truck dumps the trash into the landfill.
Example Output: trash ,truck

Example Input: A seed is in soil. The seed germinates. The plant grows roots. The plant grows out of the ground. The plant gets bigger. The plant flowers. The flower produces fruit. The fruit releases seeds. The plant dies.
Example Output:
seed ,plant ,roots ,flowers ,fruit