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高中三年级英语

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    Believe it or not, cell phones have been around for over a quarter of a century.The first commercial cell phone system was developed by the Japanese in 1979. But cell phones have changed a lot since that time. The early cell phones appeared big and heavy but they have developed into small and light palm­sized models. There have been huge developments in their functions,too. We have had call forwarding, text messaging, answering services and hands­free use for years, but now the manufacturers equip countless new facilities, such as instant access to the Internet and receiving and Sending photos.
    Cell phones have become very common in our lives;recent statistics suggest as many as one in three people on the planet now has a cell phone, and most of them say they couldn't live without one. Cell phones are used in every area of our lives and have become a necessary tool, used for essential arrangements, social contact and business. They have made it easier to call for help on the highway. They have made it possible to keep in touch with people “on the move” when people are traveling.
    Cell phones have made communication easier and have reduced the need for family arguments. We can use cell phones to let our family know we'll be late or if there's a change of plan or an emergency. Cell phones have eased the worries of millions of parents when their teenagers are out late, and they can now contact their children at any time.
    This does not mean that cell phones are all good news. They have brought with them a number of new headaches for their owners: it costs a lot to replace stolen phones, something that is becoming a frequent occurrence, and have you ever seen such huge phone bills? More serious, however, is the potential health problem they bring: there are fears that radiation from the phones may cause brain tumor(肿瘤). This may be a time bomb waiting to happen to younger people who have grown up with cell phones that they simply can't live without.

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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