一.分类:基数词和序数词
二.用法:
1.基数词:用来计数的词,除了one,用来修饰可数名词复数。
e.g. two apples
three sisters
twenty books
2.序数词:用来表示顺序的词,通常用来修饰可数名词单数,在句子中,序数词通常与the连用。
e.g. second book
twentieth game
3. 基数词转变为序数词的变化规则:
1-10 11-19(十几通 10-90(几十通常
常以-teen结尾) 以-ty结尾)
one-first eleven-eleventh ten-tenth
two-second twelve-twelfth twenty-twentieth
three-third thirteen-thirteenth thirty-thirtieth
four-fourth fourteen-fourteenth forty-fortieth
five-fifth fifteen-fifteenth fifty-fiftieth
six-sixth sixteen-sixteenth sixty-sixtieth
seven-seventh seventeen-seventeenth seventy-seventieth
eight-eighth eighteen-eighteenth eighty-eightieth
nine-ninth nineteen-nineteenth ninety-ninetieth
注意:几十几中间必须有连字符“-”,基数词变序数词只变个位,不变十位;
e.g. twenty-one: twenty-first
twenty-nine: twenty-ninth
sixty-eight: sixty-eighth
4.数词的用法:
(1)除了one,基数词通常修饰可数名词的复数;序数词通常修饰可数名词单数,通常与the连用。但出现the不一定用序数词。
e.g.There are three apples on the desk.
Look at the six pictures.
Look at the sixth picture.
(2)次数和倍数,倍数的表示:time意思为“时间”为不可数名词;意思为“次数”为可数名词。
①once“一次,一倍”,不可写为one time
②twice“两次,两倍”,不可写为two times
③基数词(大于或等于3)+times
e.g. three times三次,三倍
four to six times四到六次,四到六倍
(3)分数的表示:分子为基数词,分母为序数词;分子大于1,分母变复数;英语里面只出现真分数。
e.g.1/3: one third=one in three
2/3: two thirds=two in three
1/4: one fourth= one quarter=one in four
3/4: three fourths=three quarters=three
in four
1/2: one second=a half=one in two
注意:分数也可表示为分子,分母均用基数词,分子+in+分母。
(4)百分数的表示:百分号为percent,基数词+percent; percent只能用单数形式; 分数和百分数可以相互转换。
e.g. 20%: twenty percent
5%: five percent
(5)时刻的表示:英语里面的时刻为十二小时制;
①先读小时再读分钟,小时和分钟均为基数词;
e.g. 6:15 six fifteen
6:30 six thirty
6:45 six forty-five
②先读分钟再读小时,分钟和小时均为基数词,规则:分钟小于或等于30,为“分钟+past+小时”;分钟大于30,为“(60-分钟)+to+(小时+1)”。
e.g. 6:15 fifteen past six=a quarter past
six
6:30 thirty past six= thirty past six
6:45 fifteen to seven= a quarter to
seven
(6)百(hundred),千(thousand),百万(million)和十亿(billion)的表示:几百,几千等由“基数词+hundred/thousand/million/billion”;数以百计等有“hundreds/thousands/millions/billions +of”。
e.g.九百:nine hundred
三百亿:three million
数以千计的:thousands of
数以十亿计的:billions of
注意:这几个词前面加了基数词就不能与of连用。
(7)年份和世纪的表示:世纪后面的年代必须是整十。
e.g.在1990年:in 1990
在1998年:in 1998
二十世纪九十年代:in the 1990s
十八世纪七十年代:in the1770s
(8)年龄的表示:
e.g.二十岁: twenty=twenty years old=at the age of twenty=in one’s twenties
三十五岁:thirty-five=thirty-five years old=at the age of thirty-five
(9)页码的表示:the+序数词+page=page +序数词对应的基数词
e.g.第五页:the fifth page=page five
(10)房间,年级,班级等的表示:
e.g. 405房间:Room 405
108班:Class 108
九年级:Grade 9=Grade Nine