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History Cold War The concept of the medium tank gradually evolved into the MBT in the 1960s , as it was realized that medium tanks could carry guns ( such as the US 90 mm , Soviet 100 mm , and especially the British L7 105 mm ) that could penetrate any practical level of armor at long range .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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