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Modern MBTs seldom operate alone , as they are organized into armored units which involve the support of infantry , who may accompany the MBTs in infantry fighting vehicle s. They are also often supported by surveillance or ground-attack aircraft .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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