BG4 Statements 16-30

Progress Indicator:
Question 6 of 15

6.  Every force __________ an equal and opposite force (this leads to smoke and fire rollback and _________ layers).  (Donald W. Mitchell, Mine Fires 3rd Edition, p. 3)

Choices:
  1. generates, oxygen
  2. creates, methane
  3. produces, unstable


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