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1、英语的加减乘除,加 plus,add,加 plus(介词，作形容词时，是正的，等同于positive)add（动词）4 plus 3 equals 7.If you add 4 to 3 you get 7.Her mark was B plus。她的分数B+。,减 minus,subtract,减 minus（介词，作形容词讲时，是“负的”的意思，相当negative）subtract（动词，常与from连用）减去；扣除 12 minus 7 leaves 5.十二减去七剩五。If you subtract 3 from 5,you get 2.The temperature was min
2、us 20 degrees.温度是零下20度。,乘 multiply,乘 multiply（动词）3 multiplied by 5 is 15.三乘五等于十五。,除 divide,除 divide（动词）15 divided by 3 is 5.3 除15等于5。Three will not divide into eleven.三除不尽十一。,加减乘除的名词形式如下,1.addition 加法 2.subtraction减法 3.multiplication乘法 4.division除法,2+3=5 Two plus three is(equals,is equal to)five.5-3
3、=2 Five minus three is equal to two.32=6 Three times two is six.Three by two are six.93=3 Nine divided by three makes three.,Can you read?,(1)年号的读法：1979nineteen seventy-nine or nineteen hundred(and)seventy-nine;(2)电话号码、货币的读法：1023one o two three;1227one double two(or two two)seven;.25four dollars(and
4、)twenty-five(cents);(3)小数点的读法：13.91thirteen decimal(point)nineone;0.23=nought demical two three;,Numbers,cardinal numbers(基数词)ordinal numbers(序数词),基数词(cardinal numbers)的构成及用法:,1.112的基数词是独立单词,无规律可循。,eleven twelve,2.1319的基数词一般在39对应的基数词后加-teen构成，注意：thirteen fifteen eighteen,3.2090八个整十位数以后缀-ty结尾。注意：twen
5、ty(20)thirty(30)forty(40)eighty(80),4.“几十几“的基数词由十位数和个位数中间加 连字符“-”构成：twenty-nine ninety-seven,5.百位数和十位数之间，在英国英语要用“and”连接，在美国一般不用。three hundred and five four hundred and forty-five,6.英语中“万”及以上的表示法：53,461 fifty-three thousand,six hundred and forty-one30,045,310 thirty million and forty-five thousand,th
6、ree hundred and ten3,333,333,333,7.hundred,thousand,million,billion前有确切数词时，遵循“两个无”原则，即无“s”，无“of”。,three hundred people nine million books,8.但hundred,thousand,million,billion前无确切数词时，则遵循“两个有”原则，即有“s”和“of”。,many thousands of trees millions of birdstens of thousands of soldiers,three hundreds people thr
7、ee hundred of books,9.基数词常与名词连用构成复合定语，中间要用连字符，而且只用名词的单数形式,an 8oo-hundred-word composition a five-week holiday a 20-meter-tall building,10.基数词可以表示年代、时刻、住所、房间、教室、电话号码等。,in 1980s(1980s)=in nineteen eightiesPage three Room 403 at seven thirty in 1991(in nineteen ninety-one)in ones fifties(在某人多岁的时候）,注意下列
8、习惯表达方式：half an hour half a kilotwo and a half kilos=two kilos and a halfone or two days=one day or two eighty meters long one thousand miles away five meters deep(wide/tall/high/long),five meters in depth/width/height/length,序数词(ordinal numbers)的构成及用法:,基数词 one,two,three 的序数词分别为:first,second,third(1s
9、t 2nd 3rd),2.从第四到第十九的序数词在基数词后加“-th”注意：fifth eighth ninth twelfth,3.十位整数基数词的序数词需将词尾的“y”改为“i”，再加“eth”构成 twenty twentieth forty fortieth ninety ninetieth,4.“几十几”的数及位数以上基数词的序数词只将个位变成序数词即可one hundredthone thousandth four hundred and thirty-second,5.日期的表达一般用序数词月日March 8(th)读作：March the eighth,6.用于最高级前表示“第
10、二、第三“the second most useful the third largest city,7.second,third 等与“a“连用，表示”又一，再一”再一次a second time,8.在世纪：in the twenty-first century in the nineteenth century,概数的表示法,over/above/more than+数字 或：数字 odd(多以上）over/more than two years(两年多）above twenty pounds(磅以上）thirty odd years(30多年）=more than 30 years,2
11、.below/under/less than+数字（不足不到，以内）below six days under two hours less than 60 miles,3.about/nearly/some/toward(s)/more or less+数字数字or so/more or less(大约近，上下左右）about 90 yards nearly one tenth some fifty feet nine kilos or so more or less 20 meters=20 meters more or less,“每隔”与“每逢”的表示法：,两种结构：every+基数词
12、复数名词 every+序数词单数名词,every four days every fourth day,每四天（每隔三天）,every three linesevery third line,每三行（每隔二行）,每隔一天：every other dayevery two daysevery second day,The bus runs every five minutes.One in every twenty students is to be chosen as the representative.,一些数学公式、小数和分数的表示法：,7X3=21 Seven times/multiplied by three is twenty-one.93=3 Nine divided by three is 3.3.5 three point five,a(one)half 1/3 one third a/one fourth a/one quarter,4/5 four fifths 12/23 twelve twenty-thirds,英、美楼层的不同表示法：,
