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¡¡¡¡The results have caused a stir among geophysicists.The magnetic field is thought to originate from molten (ÈÛ»¯µÄ) iron in the outer core, 3,000 kilometres beneath the earth¡¯s surface.By studying mineral grains found in material ranging from rocks to clay articles, previous researchers have already been able to identify reversals dating back 170 million years, including the most recent switch 730,000 years ago.How and why they occur, however, has been widely debated.Several theories link polarity flips to external disasters such as meteor (ÔÉÐÇ) impacts.But Peter Olson, a geophysicist at the Johns Hopkins University in Baltimore, says this is unlikely if the French researchers are right.In fact, Olson says intensity that predictably declines from one reversal to the next contradicts 90 percent of the models currently under study.If the results prove to be valid geophysicists will have a new theory to guide them in their quest to understand the earth¡¯s inner physics.It certainly points the direction for future research.

¡¡¡¡Q£ºWhich of the following titles is most appropriate to the Passage?
¡¡¡¡A) Polarity Reversal: A Fantastic Phenomenon of Nature
¡¡¡¡B) Measurement of the Earth¡¯s Magneticª²Field Intensity
¡¡¡¡C) Formation of the Two Poles of the Earth
¡¡¡¡D) A New Approach to the Study of Geophysics
¡¡¡¡´ð°¸ÊÇA)¡£ä¯ÀÀÈ«ÎÄ·¢ÏÖһЩµØÖÊ·½ÃæµÄ´Ê²»¶Ï³öÏÖ£¬¡°polarity reversal¡±²î²»¶àÔÚÿ¶Î¶¼³öÏÖ£¬¶øB)¡¢C)¡¢D)ÏîÖ»ÊÇÎÄÕÂÉæ¼°µÄϸ½Ú£¬¹ÊÑ¡A)¡£

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¡¡¡¡A nineª²yearª²old schoolgirl singleª²handedly cooks up a scienceª²fair experiment that ends up debunking (½Ò´©¡­¡­µÄÕæÏà) a widely practiced medical treatment.Emily Rosa¡¯s target was a practice known as therapeutic (ÖÎÁƵÄ) touch (TT for short),whose advocates manipulate patients¡¯¡°energy field¡±to make them feel better and even,say some,to cure them of various ills.Yet Emily¡¯s test shows that these energy fields can¡¯t be detected,even by trained TT practitioners (ÐÐÒ½Õß).Obviously mindful of the publicity value of the situation,Journal editor George Lundberg appeared on TV to declare,¡°Age does¡¯t matter.It¡¯s good science that matters,and this is good science.¡±

¡¡¡¡Emily¡¯s mother Linda Rosa,a registered nurse,has been campaigning against TT for nearly a decade.Linda first thought about TT in the late ¡¯80s,when she learned it was on the approved list for continuing nursing education in Colorado.Its 100,000 trained practitioners (48,000 in the U.S.) don¡¯t even touch their patients.Instead,they waved their hands a few inches from the patient¡¯s body, pushing energy fields around until they¡¯re in ¡°balance.¡±TT advocates say these manipulations can help heal wounds, relieve pain and reduce fever.The claims are taken seriously enough that TT therapists are frequently hired by leading hospitals, at up to «Ã70 an hour£¬to smooth patients¡¯ energy,sometimes during surgery.

¡¡¡¡Yet Rosa could not find any evidence that it works.To provide such proof,TT therapists would have to sit down for independent testing¡ªsomething they haven¡¯t been eager to do,even though James Randi has offered more than «Ã 1 million to anyone who can demonstrate the existence of a human energy field.(He¡¯s had one taker so far.She failed.) A skeptic might conclude that TT practitioners are afraid to lay their beliefs on the line.But who could turn down an innocent fourthª²grader? Says Emily:¡°I think they didn¡¯t take me very seriously because I¡¯m a kid.¡±
The experiment was straight forward:21 TT therapists stuck their hands,palms up,through a screen.Emily held her own hand over one of theirs¡ªleft or right¡ªand the practitioners had to say which hand it was.When the results were recorded,they¡¯d done no better than they would have by simply guessing.If there was an energy field,they couldn¡¯t feel it.

¡¡¡¡Q£ºWhat can we learn from the Passage?
¡¡¡¡A)Some widely accepted beliefs can be deceiving.