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: The oil is extracted either onshore or offshore by large oil rigs. Crude oil is transported to a refinery. The refinery turns the crude oil into gasoline. The gasoline is loaded onto tank trucks. The tank trucks go to gas stations all over the place. The gasoline is delivered to the gas station. 
Example Output: oil ,gasoline 

Example Input: Air enters the nose or mouth and travels through the windpipe into the lungs. The lungs have a series of smaller and finer tubes and sacs. Air reaches the smallest and finest air sacs called alveoli. Oxygen travels from the alveoli into the blood. Oxygen-rich blood is carried to the heart. Oxygen-rich blood is pumped throughout the body by the heart. Cells take in the oxygen rich blood and release carbon dioxide rich blood. The carbon dioxide rich blood travels to the lungs. Carbon dioxide travels through the throat and is exhaled. 
Example Output: air ,oxygen ,oxygen-rich blood, oxygen rich blood ,carbon dioxide rich blood ,carbon dioxide 

Example Input: Begin the party. Partake in activities. Bring out the cake. Sing "Happy Birthday!". Blow out the candles. Eat the cake. Open the presents. 
Example Output:
cake ,candles