Instructions: 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. 
Input: Stars burn mass. The star burns until it runs out of fuel. The star can no longer support its weight. The layers of hydrogen press down on the core. The core gets smaller and smaller under the pressure. The pressure causes gravity to get stronger. The gravity becomes so powerful that nothing can escape it. Anything that gets close to it, is drawn into it by its gravity. Light is drawn into it. Light can not escape. 
Output:
Mass ,Fuel ,Gravity 