In this task, you are given a paragraph, event and an entity. The event is part of the given paragraph and it changes the state of the entity. Your task is to classify the state of the entity into three classes: 1) not exist, 2) unknown location and 3) known location. "not exist" means the entity doesn't exist in that state anymore. "unknown location" means the entity exists in that state but location is unknown. "known location" means the entity exists and location is known. 

Q:  "process paragraph : : People dig up coal from the ground. People burn coal for heat or electricity. Pollution from the coal goes into the sky. Coal pollution enters clouds. Clouds rain over an area. The polluted rain becomes acid rain. ", "event : People burn coal for heat or electricity.", "entity : coal" 

A:  not exist 
****
Q:  "process paragraph : : A radioisotope has unstable nuclei that does not have enough binding energy to hold the nucleus together. Radioisotopes would like to be stable isotopes so they are constantly changing to try and stabilize. In the process, they will release energy and matter from their nucleus and often transform into a new element. This process, called transmutation, is the change of one element into another as a result of changes within the nucleus. He radioactive decay and transmutation process will continue until a new element is formed that has a stable nucleus and is not radioactive. ", "event : Radioisotopes would like to be stable isotopes so they are constantly changing to try and stabilize.", "entity : Radioisotopes" 

A:  unknown location 
****
Q:  "process paragraph : : A red giant star forms from an existing star. Formation occurs when the star runs out of hydrogen fuel. Hydrogen atoms are combined together to form helium atoms. Energy produced by helium fusion causes the star to expand. A red giant star is the last stage of stellar evolution. ", "event : Formation occurs when the star runs out of hydrogen fuel.", "entity : hydrogen fuel" 

A:
 not exist 
****