The phrase "study at occurrence" can be rephrased using several synonyms. Some examples include "analyze when it happens," "investigate upon happening," "examine at event," and "scrutinize during incident." Each of these synonyms highlights the idea of carefully observing something that is happening or has happened, in order to gain a better understanding or potentially find a solution. It is important to use multiple synonyms so that the same phrase is not repeatedly used, and to ensure clarity in communication. By using different words to convey the same meaning, a writer can make their text more interesting and dynamic.