1.基數(shù)詞是表示數(shù)目的數(shù)字，如：

one(一), two(二), ten(十), twenty(二十), one hundred(一百), two thousand(兩千), ten million(一千萬), three billion(三十億)等。

2.基數(shù)詞可相當(dāng)于名詞，可有復(fù)數(shù)形式,這時(shí)它所表達(dá)的數(shù)量不很準(zhǔn)確,僅僅是一個(gè)大概范圍。hundred, thousand和million等的復(fù)數(shù)形式之后常接of片語，表示數(shù)以百計(jì)、千計(jì)、百萬計(jì)等;of片語有時(shí)也可省略。

I have found a way to make thousands of dollars.

我已經(jīng)找到一個(gè)賺成千上萬美元的方法。

They arrived in twos and threes.

他們?nèi)齼蓛傻膩砹恕?/p>

Hundreds of lives were lost in the fire.

數(shù)百人在大火中喪生。

Thousands and thousands of people got infected with flu every year.

每年成千上萬的人受到流行性感冒感染。

In order to maintain its operation, the company needs millions of dollars.

這個(gè)公司需要數(shù)百萬美元以維持其運(yùn)作。

3.dozen, score, hundred, thousand, billion, million之前有確定的數(shù)字時(shí)不論后面有無of，字尾都不加s。

It is two thousand of quarters, 250 dollars.

是兩千個(gè)25美分，250美元。

4.基數(shù)詞表示幾十的復(fù)數(shù)數(shù)詞的變化形式與名詞相同，一般用來表示人的不確切年齡。

I will become a famous painter in my twenties.

我將在二十歲時(shí)成為知名畫家。

He died in his early thirties.

他三十剛過就死了。

5.基數(shù)詞在句中可作主語、賓語、修飾語、主語補(bǔ)語和同位語。

Thirteen is an unpropitious number.

13是個(gè)不吉利的數(shù)字。

Seven is an odd number.

七是奇數(shù)。

基數(shù)詞Seven作主語。

I still need two.

我還需要兩個(gè)。

I need at least eight.

我至少需要八個(gè)。

基數(shù)詞eight作賓語。

Return those two coins to me!

把那兩枚硬幣還給我!

Thirty students are doing chemical experiments in this classroom.

三十個(gè)學(xué)生在這間教室里做化學(xué)試驗(yàn)。

基數(shù)詞Thirty作修飾語。

Six plus two is eight.

六加二是八。

Four plus two is six.

四加二是六。

基數(shù)詞six作主語補(bǔ)語。

Have you ever seen us two?

你見過我們兩個(gè)人嗎?

基數(shù)詞two作賓語us的同位語。