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: Fault lines appear underground. The fault lines grow over time. The rocks on each side of the fault lines rub against the rocks on the other side of the fault line. The rocks put pressure on each other. The rocks break from the pressure. The breaking of the rocks releases a lot of energy. The energy causes seismic waves. The seismic waves make the earth shake. 
Example Output: fault lines ,pressure ,rocks ,energy ,seismic waves 

Example Input: The farmer chooses a crop that will grow well in his region. The farmer tills the soil to loosen it. The farmer spreads seeds. The farmer tills again to plant the seeds. Crops grow. 
Example Output: seeds ,crops 

Example Input: The air is cold. Water is in the air. The water forms tiny ice crystals. The ice crystals collide with each other. The ice crystals stick to each other. The ice crystals get bigger as more of them stick together. The ice crystals get too heavy to be in the air. The ice crystals become snowflakes. The snow flakes fall to the ground as snow. 
Example Output:
water ,ice crystals ,snow flakes; snowflakes; snow