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1: Active solar heating system 2: Soil 3: Community 4: Feeder 5: Carbon 6: Lead 7: Current 8: Water 9: Human 10: Range 11: Process 12: Contamination 13: Environment 14: Electricity 15: Fishery 16: Condition 17: Conservation 18: Atom 19: Hazard 20: Subdivision (As of 16:27)
