Because of increases in the price of oil and because of government policies promoting energy conservation, the use of oil to heat homes fell by 40 percent from 1970 to the present, and many homeowners switched to natural gas for heating. Because switching to natural gas involved investing in equipment, a significant switch back to oil in the near future is unlikely. The prediction that ends the passage would be most seriously called into question if it were true that in the last few years ['the price of natural gas to heat homes has remained constant, while the cost of equipment to heat homes with natural gas has fallen sharply', 'the cost of equipment to heat homes with oil has fallen sharply, while the price of heating with oil has fallen below the price of heating with natural gas', 'the cost of equipment to heat homes with natural gas has fallen sharply, while the price of home heating oil has fallen to 1970 levels', 'the use of oil to heat homes has continued to decline, while the price of heating oil has fallen to 1970 levels']