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 I'd hoped for haven't 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
正确答案是

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
正确答案是

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
正确答案是

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!
正确答案是

TEXT C

Because Ireland is an island geographically near the mainland of the United Kingdom, English rulers have fought since the Middle Ages to retain political control over it.    Attracted by the lush farmland, English and Scottish landowners settled there, and in time of famine or political unrest, the local workers suffered, while their landlords were cushioned by their wealth.    The history of modern Ireland is, in fact, largely a story of antagonism and resentment between the Irish and their English and Scottish rulers.

Since the 1920's, Ireland has been divided into two parts: Northern Ireland (Ulster) and the Republic of Ireland (Eire).    The north is still part of the United Kingdom and is predominantly Protestant; the south is an independent republic and is mainly Catholic.    The majority in Ulster accepted this political compromise, but the active and mainly Catholic minority are fighting for union with the independent republic of Southern Ireland.    The IRA, the Irish Republican Army, have mounted bombing campaigns on military and civil targets in Ulster and England, they have sent letter-bombs to public figures, they have shot fellow Irishmen who support the British or belong to opposing, and now equally militant Protestant groups.    As a result of this, the British have stationed an army in Belfast, the IRA have been outlawed, and several of them have spent many years in prison or have died in support of their cause.    Whether this level of violence and repression is justifiable, and whether the violence that could result from political change would be worthwhile are the controversial issues that divide everybody involved.