TEXT B In 1983, when oil prices were still high in my area, I installed a ground-source heat pump in my brand-new, well insulated 1,600-square-foot house. It cost several thousand dollars more than comparable systems that use oil, gas, or wood, but I figured Id recover my higher initial expense in a few years through lower energy bills. True, my heat pump runs on electricity —— an expensive commodity where I live. But most of its energy comes from the earth: a propylene-glycol solution circulates through 1,200 feet of two-inch-diameter plastic pipe buried three feet deep in a field next to my house. As it travels, the solution absorbs heat from the surrounding soil, even when soil temperature drops below freezing. My ground-source heat pump also offers important benefits that have nothing to do with economics. · Minimal fire hazard —— no chimney, firebox, or heating elements —— only pumps, fans, and a compressor. · Cleanliness —— no combustion products, thus no chance of my heating system polluting the indoor air, leaving scummy deposits on walls and furniture. · Reliability —— solid-state electronic controls and sealed bearings almost eliminate breakdowns. · No maintenance —— no wood to cut, ashes to haul, or chimney to clean. · Convenience —— The system runs automatically, even switching from heating to air conditioning as needed. I can simply lock the door and go away for a day, week, or month. Not only did I expect to start saving on energy costs immediately, but I also expected those savings to grow over the years as oil prices continued to soar. Since I was wrong about oil prices, the big dollar savings Id hoped for havent materialized. Nevertheless, I am satisfied, all things considered.
　　69. The passage suggests that the author's heat-pump system absorbs heat from _____.
　　A) soil in a nearby field
　　B) sun panels at ground level
　　C) a pipe buried next to the walls
　　D) a tank of propylene-glycol
　　70. According to the passage, the author's heat pump requires _____.
　　A) no maintenance
　　B) very little maintenance
　　C) only a yearly check of controls
　　D) no more maintenance than an oil burner
　　71. Once benefit the author mentions is that the system _____.
　　A) uses no electricity
　　B) has a fire-safety shutoff
　　C) does not pollute the air in the house
　　D) requires less insulation in house walls
　　72. The best title for the passage is _____.
　　A) Preparing the Ground for a Pump System
　　B) Pros and Cons of the Ground-Source Heat Pump
　　C) How to Know Whether an Oil Burner is Right for Your Home

　　D) The Ground-Source Heat Pump: It Works for Me!