2015年考研英语阅读理解考前专项训练（123）
发布时间：2012/11/7 15:01:42 来源：城市网学院 编辑：admin
The environment contains three major natural sources of radiation：radioactive elements in mineral deposits，uhraviolet light from the Sun，and cosmic rays.The carcinogenic potential of radioactive elements and ultraviolet light has been established，while that of highly energetic cosmic radiation remains to be documented.Clearly，chronic exposure to intense sunlight is fl major cause of skin cancer in humans；incidence is high in farmers，sailors，and habitual sunbathers.Since the most effective natural screen for uhraviolet light is the natural skin pigment，melanin，individuals with large amounts of melanin--blacks，for example--are resistant to the carcinogenic effects of uhraviolet light.Fair- #plexioned people，on the other hand，are quite susceptible.It is important to point out that the term skin cancer，as it is generally used，includes not only malignant tumours of the nonpigmented cells of the skin but also tumours of the pigmented cells（melanoma）。Under the proper conditions ultraviolet light can cause cancer to develop in the very cells that produce the pigment that affords protection from solar radiation.①
The environment also contains dangerous ionizing radiation from artificial sources.These include X- rays used for medical diagnosis and therapy，radioactive chemicals，radioactive elements used in atomic reactors，and radioactive fallout arising from the testing of nuclear devices.Home appliances have been known to emit potentially harmful X-rays under certain circumstances，as was the case with soree colour television sets made during the l950s.。Radiation leaks from improperly constructed or operated microwave ovens can also occur，but the health hazards from such exposures have yet to be established. Certain medical applications of X-rays，such as those used to establish the size and position of a fetus before birth and to control acne，have been largely abandoned because of the increased risk of cancer.o Modern technology has greatly reduced the risk of diagnostic X-rays，however.During therapeutic x- irradiation for the treatment of cancer。great care is taken to focus radiation on the tumour and to shield the adjacent normal body tissues from undue exposure.Laboratory workers who use radioactive chemicals are careful to prevent undue exposure by contamination and to dispose of radioactive wastes properly.The cancer risk from radioactive fallout resulting from the testing of atomic devices is virtually impossible to establish with certainty because of the large geographic areas affected.In general，such exposure is not massive，and immediate effects are probably not of high significance.The absorption by growing crops and farm animals of long-lived radioactive isotopes，such as strontium，from fallout may pose a threat to humans，however，because the crops and animals are a source of food.[432 words]
1.The underlined word“that”in the first paragraph refers t0______.
A.ultraviolet light
B.radioactive element
C.carcinogenic potential
D.cosmic ray
2.The first paragraph is mainly about______.
A.three major natural sources of radiation
B.a major cause of skin cancer
C.the carcinogenic effects of cosmic radiation
D.the association of environmental radiation with skin cancer
3.The author believes that______.
A.white people are more vulnerable to radiation than blacks
B.chronic exposure to intense cosmic radiation rarely causes cancer
C.the radiation from natural sources is more harmful than that from artificial ones
D.the radiation from natural sources is less harmful than that from artificial ones
4.According to this passage，______.
A.radiation leaks from improperly operated microwave ovens have little immediate effect on human health
B.radiation leaks from improperly operated microwave ovens have fatal effect on human health
C.the radiation emitted by some home electronic appliances may be potentially harmful
D.the cancer risk from all the medical applications of X-rays has been considerably reduced
5.It can be inferred from the passage that______.
A.even brief exposure to radioactive fallout will cause cancer
B.radioactive fallout may harm humans in the long run
C.the cancer risk from radioactive fallout has been ruled out
D.long-lived radioactive isotopes rarely produce significant effects on human health [NextPage] 难句透析
①Under the proper conditions ultraviolet light can cause cancer tO develop in the very cells[that produce the pig ment（that affords protection from solar radiation）].
【结构】本句是主从复合句，主句的主语是“ultraviolet light”；形容词“very（正是的，恰好的）”强调“cells”。方括号标示的部分是“cells”的后置定语从句；圆括号标示的部分是“pigment”的后置定语从句；“protection”后面常跟介词“from”。
【释义】皮肤色素有助于抵御太阳辐射。在适当条件下，紫外线恰恰能使产生皮肤色素的细胞致癌……
②Home appliances have been known to emit potentially harmful X—rays under certain circumstances，Eas was the case with some colour television sets made during the 1950s].
【结构】本句是主从复合句。关系代词“as”引导的非限制性定语从句修饰整个主句。过去分词短语“made during1950s”用做后置定语，修饰“television sets”。
【释义】现在已经知道，在一定条件下，家用电器可能会发出有害的x射线。20世纪50年代生产的某些彩电就是如此。
③Certain medical appliances of X—rays，such as those Eused“—to esta—blish the size and position of a fetus before birth and”to control acne]。have been largely abandoned because of the increased risk of cancer.
【结构】本句中，“those”指的是“medical appliances of X—rays”；过去分词短语“used…acne”用做后置定语，修饰“those”；两个并列的动词不定式短语“to establish…”和“tO control acne”用做状语。
【释义】某些使用x射线的医疗设施可以用来在产前确定胎儿的大小和位置，也可用来治疗痤疮。但是由于这些医疗设施有很大的致癌风险，所以大多已被淘汰。
全文翻译
我们生存的环境中存在三种自然的放射性城市网：矿藏中的放射性元素、太阳的紫外线以及宇宙射线。放射性元素和紫外线对致癌的影响已经很明确了，而高能宇宙射线对癌症形成的影响还需要进一步记录观察。很明显的，长时间暴露在高强度的太阳光下是造成人类皮肤癌的主要原因；这通常在农民、海员和有晒目光浴习惯的人群中高发。由于最有效的防护紫外线的保护膜就是自然形成的皮肤色素，黑色素。因此黑色素含量较高的人群——比如说黑人…就对紫外线的致癌作用有抵抗力。而从另一方面看，肤色白皙的人群则容易受到影响。值得指出的是，我们通常意义上所说的皮肤癌不仅包括无色素皮肤细胞的恶性肿瘤，同时还包括有色索皮肤细胞的肿瘤（黑素瘤）。皮肤色素有助于抵御太阳辐射。在适当条件下，紫外线恰恰能使产生皮肤色素的细胞致癌。
环境当中也存在由人工制品放射出来的危险的电离射线。这当中包括医疗诊断和康复过程中所用的x射线、放射性化学药品、原子反应堆中的放射性元素以及核设施试验过程中的放射性泄漏物等。现在已经知道，在一定条件下，家用电器可能会发出有害的X射线。20世纪50年代生产的某些彩电就是如此。做工不正确或是使用不得当的微波炉也存在放射性物质泄漏的情况，但是由此带来的健康危害还需要进一步鉴定。
某些使用x射线的医疗设施可以用来在产前确定胎儿的大小和位置，也可用来治疗痤疮。但是由于这些医疗设施有很大的致癌风险，所以大多已被淘汰。但是，现代科技的发展已经使得医疗诊断中所用的X射线的危险大大降低。在针对癌症的康复性X光放疗中，放射线已经很集中地施用在肿瘤部位，同时非常注意保护临近的正常肌体组织不被暴露在放射线下。实验室中使用放射性化学药品的人员也需要小心预防因污染造成的不必要的暴露，并且也要对放射性废料进行恰当的处置。由测试原子能设备而泄漏的放射性物质致癌的可能性无法进行准确的判断，这是由于受影响的地域过于宽广。总而言之，这样的暴露涉及面不广，而且当时所产生的后果或许根本无关紧要。但是，庄稼以及农场放养的动物对长效放射性同位素，比如说锶的摄入，则可能对人类造成威胁，因为庄稼和动物都是人类的食品城市网。
超纲词汇
Acne n.痤疮，粉刺
leak n.泄漏
Carcinogenic 致癌物（质）的
fair-#plexioned 白皙肤色的
fallout n.辐射灰尘，原子尘，附带结果
ionize vt.／vi.使离子化，电离
irradiation n.放射，照射
melanin n.[生化]黑色素
nonpigmented adj.元色素的
pigment n.色素，颜料
strontium n.锶
susceptible adj.易受影响的，易感动的，容许…的
undue 不适当的
参考答案：1.C 2.D 3.A 4.C 5.B
