60. One of the more reliable methods of determining regional climatic conditions in prehistoric periods is to examine plant pollen trapped in glacial ice during ancient times. By comparing such pollen samples with spores take from modern vegetation, scientists can figure out approximately what the weather was like at the time of pollen deposition. Furthermore, by submitting the prehistoric samples to radiocarbon dating techniques, we can also determine when certain climatic conditions were prevalent in that portion of the globe.
Which one of the following may be inferred from the information in the passage?
(A) The earth has undergone several glacial periods.
(B) Radiocarbon dating can be corroborated by glacial evidence.
(C) Similarities between prehistoric and contemporary climates do not exist.
(D) Pollen deposition is a fairly continuous process.
(E) Certain flora are reliably associated with particular climatic conditions.
61. Investigators concluded that human failure was not responsible for the fatal airplane crash last August, and since that time new and more stringent rules for identifying and reporting mechanical problems have been in effect. That accounts for the fact that reports of airplane mechanical problems have increased in frequency by 50 percent since last August.
Which one of the following is an assumption underlying the argument in the passage?
(A) Airplane travel is still relatively safe, despite the increase in reported mechanical problems.
(B) Mechanical problems in airplanes have increased dramatically since last August.
(C) Mechanical problems in airplanes have not increased by 50 percent since last August.
(D) Airlines are less reluctant to report mechanical problems than they previously were.
(E) Mechanical problems in airplanes have become easier to detect since last August.
62. Brushing your teeth regularly no matter which toothpaste you use, will reduce your chances of tooth decay. Scientists have concluded that, when you brush, you reduce tooth decay by removing the film of plaque that forms on teeth and gums. So, you can forget about fluorides: brush your teeth carefully and say goodbye to cavities.
Which one of the following is a criticism of the reasoning in the argument?
(A) Brushing with fluoride toothpaste has been shown to reduce tooth decay.
(B) The fact that brushing will reduce tooth decay does not show that fluorides are of no value.
(C) Few people adequately remove plaque by brushing.
(D) People have plaque on their teeth most of the time.
(E) Scientists have been wrong about fluorides.
第60题的答案是E，我觉得E选项和原文没有什么关系呀，我觉得D更对！
第61题的答案是C，我觉得A也没错呀，我选的是A.
第62题的答案是B，我觉得C也对呀。原文已经说了by removing the film of plaque，所以我才认为C对。
请高人帮我讲解一下！十分感谢！！！
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