人教版高中英语选修英语语法与词汇NUMBERSANDQUANTITIES.ppt

NUMBERS AND QUANTITIES Read and Answer 1. HIV infections are increasing at a meaningful rate among migrant workers in Mexican.( ) 2. What was the rate of HIV infections among women giving birth at Tijuana General Hospital? T The rate was four times higher than that in the general population of either country. 3. As much as 2000 people are infected with HIV， according to the results of a study of 600 migrant workers in California’s Fresno and San Diego counties. ( ) F 数词 1.定义：表示数量或顺序的词叫做数词。 2.分类：表示人或事物数量多少的数词叫 基数词，如one，two，three，ten等；表示 人或食物顺序的数词叫序数词，如first， second，fourth等。 A.基数词 1.构成： (1)1~12记成：one，two，three…twelve。 (2)13~19词尾为teen，thirteen，fourteen，fifteen (3)20，30，40逢10词尾为ty，twenty，thirty (4)21~99十位数字和个位数字之间加连词符，twenty-one (5)101~999先说几百，再加and，再加末尾两位数(末位数) eg：178 one hundred and seventy-eight. (6)大数的表达：hundred，thousand，million等词在表示 具体数量的时候用单数；表示“成……上……”要用复数， 例如；thousands of成千上万的 2.位置： (1) 位于another，all之后，如： Can I have another two cakes？ (2) 可置于last，next，other之前或之后，如： His last two books are written in English. =His two last books are written in English. 他的后两本书是用英语写的。 B.序数词 1.常见的序数词：first---1st；second---2nd；third-3rd； thirty-first---31st。 2.序数词的构成方法口诀: 一，二，三要全变；(one-first; two-second; three- third) 其余都加th, th里有例外，8去t, (eight-eighth) 9去 e(nine-ninth) 字母f代ve (five-fifth; twelve-twelfth); ty变成 tie(twenty-twentieth) 若要变化几十几，只变个位就可以(twenty-one twenty-first) 3.用法： (1)一般情况下，序数词前面要加定冠词the 例：I have already got two letters from Susan this year, so this is the third one. (2)序数词前加定冠词和冠词的区别： 例：I’ll go to Beijing a third time next month.（已 经去过两次了。 I have a fourth apple.（我已经吃了三个，又 吃了一个，a fourth one.） The third time I went to Beijing was in 1998. C.英语中小数、百分数和分数的表达 1.分数：分数的构成总则为：分子用基数词，分母用 序数词，中间用连词符连接。 ①分子为1的分数，分子用基数词，分母用序数词，如： 1/3 one-third 1/3 one-fourth ②分子大于1的分数，分母的序数词要加s，如： 2/3 two-thirds 3/5 three-f