In an uncritical August 11, 1997, World News Tonight report on "diamagnetic therapy," a physical therapist explained that "magne

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问题     In an uncritical August 11, 1997, World News Tonight report on "diamagnetic therapy," a physical therapist explained that "magnets are another form of electric energy that we now think has a powerful effect on bodies." A fellow selling $ 89 magnets proclaimed: "All humans are magnetic. Every cell has a positive and negative side of it."
    On the positive side, these magnets are so weak that they cause no harm. On the negative side, these magnets do have the remarkable power of attracting the pocketbooks of gullible Americans to the tune of about $ 300 million a year. They range in scale from coin- sized patches to mattresses, and their curative powers are said to be nearly limitless, based on the premise that magnetic fields increase blood circulation and enrich oxygen supplies because of the iron pressure in the blood.
    This is fantastic flapdoodle and a financial flimflam. Iron atoms in a magnet are crammed together in a solid state about one atom apart from one another. In your blood only four iron atoms are allocated to each hemoglobin molecule, and they are separated by distances too great to form a magnet. This is easily rested by picking your finger and placing a drop of your blood next to a magnet.
    What about claims that magnets attenuate pain? In a 1997 Baylor College of Medicine double-blind study of 50 patients (in which 29 got real magnets and 21 got sham ones), 76 percent in the experimental group but just 19 percent in the control group reported a reduction in pain. Unfortunately, this study included only one 45-minute treatment, did not try other pain-reduction modalities, did not record the length of the pain reduction and has never been replicated.
    Scientists studying magnetic therapy would do well to read the 1784 "Report of the Commissioners Charged by the King to Examine Animal Magnetism" (reprinted in an English translation in Skeptic, Vol. 4, No. 3). The report was instituted by French King Louis XVI and conducted by Benjamin Franklin and Antoine Lavoisier to experimentally test the claims of German physician Franz Anton Mesmer, discoverer of "animal magnetism." Mesmer reasoned that just as an invisible force of magnetism draws iron shavings to a lodestone, so does an invisible force of animal magnetism flow through living beings.  
There is no magnet in blood because ______.

选项 A、there is only one hemoglobin molecule in blood
B、there are only four iron atoms in blood
C、the iron atoms in blood are allocated to each hemoglobin molecule only
D、the iron atoms in blood are far away from each other to form a magnet

答案D

解析 细节题型见第三段第三句:In your blood only four iron atoms are allocated to each hemoglobin molecule, and they are separated by distances too great to form a magnet. 在四个选项中只有选项D与这句子是同义。(在你的血液中每个血色素分子只分配到四个铁原子,而且它们之间的距离大到无法形成一个磁体)因此选项D为答案。
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