阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。

　　Microwaves may be great at warming up food, but what about warming people?

　　Using microwaves to directly heat owners of a room would save much of the energy wasted by heating walls and furniture．And despite popular ideas about microwaves, this technique would be safe, according to Charles T．Burlier of the Microwave Research Centre in Marlborough, New Hampshire．Low-power microwaves only penetrate(贯穿)the skin(low-power microwave penetration in a ham is about 0.2 inches, for example)and with no negative effects．

　　To test this idea, Buffer subjected himself to microwaves in a special room using a standard 500-watt, 2459 MHz magnetron(磁控管)．He found that a person would start to feel warmth at about 20 milliwatts per square centimeter(mw．/sq．cm．)； a satisfactory feeling of warmth occurs between 35 and 50 mw．/sq．cm．By comparison, a person standing in noonday summer sun feels the amount of 85 mw．sq．cm．And a frozen meat pie in your microwave oven receives about 1000mw．/sq．cm．

　　In houses of the future, each room could be provided with its own magnetron, says Buffler．When you stepped into the living room, for example, a motion detector would turn on the magnetron, filling the room with low-power microwaves．In the same way that a microwave oven heats up a hamburger, but not the plate it's on, you would feel warmth from the microwaves without changing the temperature of your coffee table．

　　While it might be some time before homeowners are comfortable enough with the idea to set up whole-body microwave heaters in houses, Buffler says microwaves may attract livestock(家畜)farmers．Lambs that are born outdoors in winter, for example, are frequently lost to cold．Microwaves could warm the lambs safely and quickly．

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完形填空

　　Building a house costs quite a lot of money．　　1　　 you plan to build a house．Your first step will be to find a right piece of land．Your 　　2　　 will depend on many different things．You will probably try to find a sunny place, with 　　3　　 surroundings near shops and bus stops, not too far from your friends and the 　　4　　 where you work．

　　Next you will find an excellent 　　5　　, and together with the builder you will work out a plan．The builder will draw the plan．It will 　　6　　 the number of rooms, their position and size, and other 　　7　　 which must be noticed, 　　8　　 windows, doors, and electric outlets．The builder will 　　9　　 how much money is 　　10　　 to build your house．He will work out the　　11　　of the　wood, bricks, the glass, and 　　12　　 else that must be used in building the house．Later on, when he starts to build, this estimate(预算)must be corrected and revised(修正)．His estimate is based on existing 　　13　　, but prices of such things may 　　14　　, and many other things may happen between the time when he 　　15　　 the estimate and the time when he builds the house．

　　When the builder 　　16　　 his estimate, you may wish to change your plan．(You may also wish to change your builder, if his estimate is too 　　17　　!)You may find that some of the features(特征)you wanted at first 　　18　　 too much, or that you can spend a little more and 　　19　　 something to your plan．The builder's estimate depends on the plan,　　20　　 the final plan depends on the builder's estimate．

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