英語(yǔ)序數(shù)詞前面不一定都要加the，應(yīng)視情況而定。當(dāng)序數(shù)詞單純地表示“第幾”的時(shí)候就加the，當(dāng)序數(shù)詞用于“又一”的意思時(shí)則用a，當(dāng)序數(shù)詞前有人稱代詞時(shí)，不加the。

序數(shù)詞什么情況下不加the

1．當(dāng)序數(shù)詞前有形容詞性物主代詞或名詞所有格修飾時(shí),序數(shù)詞前不用the.

Mother was my first teacher in my life.媽媽是我生命中的第一個(gè)老師.

Tom is Lily's third boyfriend.湯姆是莉莉的第三個(gè)男朋友.

2．當(dāng)表達(dá)分?jǐn)?shù)時(shí),序數(shù)詞前不用the.

One fifth of the students here are from the country.這兒1/5的學(xué)生來(lái)自農(nóng)村.

Three fourths of the students here are from the country.這兒的3/4的學(xué)生來(lái)自農(nóng)村.

3．當(dāng)表達(dá)“又一,再一”時(shí),序數(shù)詞前不用the,但可加不定冠詞.

Please give me a second chance.請(qǐng)?jiān)俳o我一次機(jī)會(huì).

The poor woman had a third baby.那個(gè)可憐的婦女又生了第三個(gè)寶寶.

4．當(dāng)表達(dá)“年月日”時(shí),尤其在朗讀時(shí),序數(shù)詞前要加the.

He was born on June 6th,1974.他出生在1974年6月6日.

5．當(dāng)序數(shù)詞在句中作狀語(yǔ)時(shí),序數(shù)詞前不用the.

Who got there second?誰(shuí)第二個(gè)到那兒的?

I finished the work first.我最先完成那項(xiàng)工作.

6.當(dāng)表達(dá)考試（賽跑等）中獲得的名次時(shí),序數(shù)詞前不用the.

She stands first in her class.她在班上成績(jī)排名第一.