在指定的文本中找到所有由3个或3个以上的大写字母组成的单词。

在下面的文本中找到单词：ACRONYM、NASA、FBI
“All sets of letters we call words are, of course, opposable to sets of non-letter symbols. But in any given language or culture, a relatively small proportion of these sets of letters are actually used to make words. For example, the United States Government’s Federal Bureau of Investigation (FBI) and the National Aeronautics and Space Administration (NASA) both have six-letter acronyms for names themselves designed to be as memorable and fast to recite as possible.”
ACRONYM, NASA, FBI.