1. geología   chemistry   algebra   geology   geography   Hint Half-n-half Clue   2. psicología   zoology   geology   psychology   history   Half-n-half Clue   3. astronomía   calculus   physics   astronomy   geology   Half-n-half Clue   4. cálculo   geometry   biology   calculus   geography   Half-n-half Clue   5. biología   biology   astronomy   chemistry   geography   Half-n-half Clue   6. zoología   zoology   philosophy   history   chemistry   Half-n-half Clue   7. historia   history   calculus   geology   biology   Half-n-half Clue