Heroes In Science

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Across
  1. 1. can keep people safe from disease
  2. 4. the act of finding or learning something for the first time
  3. 6. materials from which everything in the universe is made
  4. 7. a test to prove a fact
Down
  1. 2. something new
  2. 3. very poor
  3. 5. someone who works for free
  4. 6. to begin