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1: Active solar heating system 2: Soil 3: Community 4: Feeder 5: Lead 6: Carbon 7: Current 8: Human 9: Water 10: Process 11: Range 12: Contamination 13: Environment 14: Fishery 15: Electricity 16: Condition 17: Conservation 18: Atom 19: Subdivision 20: Plant (As of 09:41)