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During the high - level Cu exposure , fish pre - exposed to copper had a significantly longer time - to - death than did the control fish .
 Chemical: Cu; Chemical: copper
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: Cu, copper 
Answer:
 Chemical: Cu; Chemical: copper