序數(shù)詞的概念:
表示順序的數(shù)稱為序數(shù)詞。如:first, second, third, fourth。
序數(shù)詞的構(gòu)成與用法:
1、序數(shù)詞的構(gòu)成:
、僖话銇碚f,是由相應(yīng)的基數(shù)詞加詞尾th構(gòu)成。
例:four+th→fourth
six+th→sixth
seven+th→seventh
ten+th→tenth
②下面這些基數(shù)詞在變?yōu)樾驍?shù)詞時(shí),有特殊的變化。
例:one→first
two→second
three→third
five→fifth
eight→eighth
nine→ninth
twelve→twelfth
、凼徽麛(shù)序數(shù)詞的構(gòu)成方法是將基數(shù)詞的詞y變成i,然后再加eth。
例:twenty→twentieth
thirty→thirtieth
forty→fortieth
ninety→ninetieth
、軆晌换騼晌灰陨系幕鶖(shù)詞變成序數(shù)詞時(shí),僅將個(gè)位數(shù)變成序數(shù)詞。
例:twenty-one→twenty-first
thirty-five→thirty-fifth
a hundred and fifty-three→a hundred and fifty-third
2、序數(shù)詞的用法:
①序數(shù)詞在使用時(shí),一般加上定冠詞。
例:the first book
the second floor
the third day
the fourth week.
、谛驍(shù)詞在多數(shù)情況下都用作定語,有的也可以作表語、主語和賓語。
例:The may1st is Labour Day. 五月一日是勞動(dòng)節(jié)。
My room is on the second floor. 我的房間在二樓。
The first is larger than the secon.(主語)第一個(gè)比第二個(gè)大。
Read the book from the first.(賓語)從開頭讀這本書。
You'll be the sixth to write.(表語)你將是第六個(gè)寫的。
、坌驍(shù)詞的前面可以加上不定冠詞,用來表示“再一”,“又一”的意思。
例:You may have a third try. 你可以第三次嘗試。
序數(shù)詞知識(shí)體系:
約數(shù)的表達(dá)方法:
用tens/dozens/scores/hundreds/thousands/millions of 表示“幾十、幾百、上千、成千上萬”等。
如:The boy bought dozens of pencils.
Thousands of people died in the earthquake.
注意: (A):dozen, score, hundred, thousand, million等表示確切數(shù)量時(shí),不用復(fù)數(shù)。
如:five dozen (of) eggs 五打雞蛋
hree hundred people 三百個(gè)人
分?jǐn)?shù)詞的構(gòu)成和用法:
1)分?jǐn)?shù)詞構(gòu)成法:
分?jǐn)?shù)詞(FractionalNumerals)由基數(shù)詞和序數(shù)詞構(gòu)成,基數(shù)詞代表分子,序數(shù)詞代表分母。除了分子為1的情況下,序數(shù)詞都要用復(fù)數(shù)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
此外還有下面表示法:
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