18. #弌仍舒亶亟 16 亅亅亅亅 D + X = D + X D + 丿 = D + C D + D = D + D D + Me = D + Me
19. 弌 Na 2 SO 4 , CaCO 3 亅亟亞 亟舒于仆 亳仄亳亶仆 亳仆亢亳亶亞 亳仍亳亶仍仆 于舒仍仆 亞亳亞仍 弍亳亶!
20. #弌仍舒亶亟 16 弌 1. H 2 CO 3 + ? = Na 2 CO 3 + H 2 2. H 2 CO 3 + ? = Na 2 CO 3 + H 2 O 3. H 2 CO 3 + ? = Na 2 CO 3 + H 2 O 4. H 2 CO 3 + ? = Na 2 CO 3 + Hcl 5. NaBr + ? = Na 2 CO 3 + CaBr 2 6. CuCO 3 + ? = Na 2 CO 3 + Cu 7. Na 2 O + ? = Na 2 CO 3 8. Na 3 PO 4 + ? = Na 2 CO 3 + H 2 O 9. CO 2 + ? = Na 2 CO 3 = H 2 O 10. Na + ? = NaCl
21. 亅亅亅亅 1.X + Me = D + H 2 2. X + C = D + H 2 O 3. X + C.O = D + H 2 O 4. X + D = D + X 5 D + D = D + D 6. D + Me = D + Me 7. C.O +X.O = D 8. D + C = D + C 9. X.O + C = D + H 2 O 10. Me + Meb = D .