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高中二年级英语

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  • 完形填空
    Radioactive(放射性的) pollution can be said to be the emission(排放) of radioactive substance into air, water or land due to human activities in the form of radioactive waste. Radioactive waste is usually the product of nuclear fission(核裂变), which is widely used in nuclear power stations and nuclear weapons.
    The radioactivity of nuclear waste decreases with time. That means the waste needs to be separated from the reach of living beings until it no longer causes a threat to living beings. This time period may take from days to months and to years depending upon the radioactive nature of the waste.
    Radioactive pollution that is spread through the earth’s atmosphere is called ‘fallout’. Nuclear pollution began to attract people’s attention during the World War II period when the United States, Britain and the Soviet Union started conducing nuclear tests. The best example of fallout is the nuclear bomb attack on Hiroshima and Nagasaki, Japan in 1945 by the United States of America during World War II. As a result of the bomb attack, nearly 225,000 people died within 5 years of the attack due to the radiation effects and cancer.
    In land and water, the major source of radioactive pollution remains with the nuclear fuel cycle(核燃料循环). The nuclear fuel cycle is used in nuclear power stations and extraction(提炼) of materials from nuclear substance, where the pollutants are left behind after the useful material has been extracted.
    The effects of radioactive pollution were first reported in the early 20th century when people working in uranium mines(铀矿井) suffered from skin burn and cancer. The effects vary from one individual to another. Exposed to radioactive radiations for a long time, living beings may suffer from the damage to the DNA cells, which results in cancer, genetic defects for the generations to come and even death.
    In a word, since every coin has its two sides, it’s a good idea to prevent from its disadvantages while making full use of its advantages.
     Title
              Radioactive Pollution and Its Effects
    小题1:    of radioactive pollution
    * It is the emission of radioactive substance.
    * Its waste is the product of nuclear fission.
    The decrease of the radioactivity
    * It decreases as time 小题2:        by.
    * The waste needs to be 小题3:        from living beings until it no longer does 小题4:        to living beings.
    * The time period of the decrease小题5:        on the radioactive nature of the waste.
    The 小题6:    of radioactive pollution
    * In 1945, the nuclear bomb attack caused 225,000 小题7:       .
    * In the early 20th, the miners suffered from skin burn and cancer and the effects are 小题8:       .
    * A long 小题9:      to radioactive radiations can damage the DNA cells.
    Conclusion
    * We should小题10:     its disadvantages and make full use of its advantages.
     

    本题信息:英语完形填空难度一般 来源:未知
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序数词

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  • 序数词

序数词的概念:

表示顺序的数称为序数词。如:first, second, third, fourth。


序数词的构成与用法

1、序数词的构成:
①一般来说,是由相应的基数词加词尾th构成。
   例:four+th→fourth
           six+th→sixth
           seven+th→seventh
           ten+th→tenth
②下面这些基数词在变为序数词时,有特殊的变化。
例:one→first
        two→second
        three→third
        five→fifth
        eight→eighth
        nine→ninth
        twelve→twelfth
③十位整数序数词的构成方法是将基数词的词y变成i,然后再加eth。
例:twenty→twentieth
        thirty→thirtieth
        forty→fortieth
        ninety→ninetieth
④两位或两位以上的基数词变成序数词时,仅将个位数变成序数词。
例:twenty-one→twenty-first
        thirty-five→thirty-fifth
        a hundred and fifty-three→a hundred and fifty-third

2、序数词的用法:
①序数词在使用时,一般加上定冠词。
例:the first book
        the second floor
        the third day
        the fourth week.
②序数词在多数情况下都用作定语,有的也可以作表语、主语和宾语。
例:The may1st is Labour Day. 五月一日是劳动节。
        My room is on the second floor. 我的房间在二楼。
        The first is larger than the secon.(主语)第一个比第二个大。
        Read the book from the first.(宾语)从开头读这本书。
        You'll be the sixth to write.(表语)你将是第六个写的。
③序数词的前面可以加上不定冠词,用来表示“再一”,“又一”的意思。
例:You may have a third try. 你可以第三次尝试。


序数词知识体系:

 


约数的表达方法

用tens/dozens/scores/hundreds/thousands/millions of 表示“几十、几百、上千、成千上万”等。
如:The boy bought dozens of pencils.            
        Thousands of people died in the earthquake.
注意: (A):dozen, score, hundred, thousand, million等表示确切数量时,不用复数。
如:five dozen (of) eggs   五打鸡蛋
        hree hundred people  三百个人

分数词的构成和用法:

1)分数词构成法:
分数词(FractionalNumerals)由基数词和序数词构成,基数词代表分子,序数词代表分母。除了分子为1的情况下,序数词都要用复数形式:
如:1/4:one-fourth
        5/9:five-ninths
        2/3:two-thirds
       17/5:three and two-fifths
       7/12:seven-twelfths
       379/8:forty-seven and three-eighths
此外还有下面表示法:
如:1/2:a(one) half
        1/4:a(one) quarter
        3/4:three-quarters
        9/4:two and a quarter
        3/2:one and half
        31/4:seven and three quarters


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