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Nano-thermite is present in the debris from the World Trade Center. But if that is so, then the buildings were brought down by controlled demolition. Therefore, the buildings were brought down by controlled demolition. (N, B)

Translate the following arguments into symbolic notation and then interpret them in light of the eight argument forms presented in this section. In some cases a symbolized argument must be rewritten using commutativity or double negation before it becomes an instance of one of these forms. Those not having a named form are invalid. The letters to be used in translating the statements are given in parentheses.