在學完定語從句之後,同學們會接觸到的另一個語法項目是數詞。表示數目、多少和順序先後的詞叫數詞。數詞有兩種:表示數目多少的數詞叫基數詞,如:one,ten twenty-three;表示順序先後的數詞叫序數詞,如:first,third,twentieth。
1.基數詞
基數詞相當於名詞,在句中可做主語、表語、定語、狀語等。如:
Three of my classmates are from Shanghai.
I am twenty this year.
They have four classes in the morning and three in the afternoon.
2.序數詞
1)序數詞的構成:
★大多數的序數詞是由基數詞加-th構成。如:seven—seventh;ten—tenth
★以-t結尾的基數詞只在詞尾加-h。如:eight—eighth
★以-ve結尾的基數詞改-ve爲f再加-th。如:five—fifth;twelve—twelfth
★以-y結尾的基數詞改-y爲-ie再加-th。如:twenty—twentieth,thirty—thirtieth
★幾十幾的序數詞只在個位數體現。如:twenty-one—twenty-first;thirty-three—thirty-third
★特殊的序數詞:
one—first;two—second;three—third; nine—ninth
2)序數詞在句中同樣可做主語、表語、定語、狀語等。如:
June the first is Children’s Day.
When did you first meet each other?
She was the last to arrive.
3.數詞的用法:
1)表示年、月、日,“年”用基數詞,“日”用序數詞。如:May eleventh,2007
2)表示時間。如: It’s eleven twenty.
3)表示編號。編號既可以用基數詞表示,也可以用序數詞表示。區別是基數詞用在名詞之後,序數詞位於名詞之前,並加定冠詞。如:Lesson Nine;the Ninth Lesson
4)介詞in one’s+整數數詞的複數形式,表示年齡。如:
She is in her early forties.(她四十出頭。)
5)序數詞前加冠詞“a”表示“再一次”。如:Can I try a second time?
6)在hundred,thousand,million,billion前有數詞時爲實數意義,它們的詞尾不能加複數。前無數詞時爲虛數意義,hundred,thousand,million,billion可加複數,並可和of連用,構成短語。如:five hundred students;millions of people
4.分數的構成
分子用基數詞,分母用序數詞,分子大於1時,分母加s,如:
1/5:one fifth
2/3:two thirds
2-:two and three quarters
5.小數的表示法
0.09:point zero nine
2.7:two point seven
6.百分數的表達法
90%:ninety percent
0.5%:point five percent
7.倍數表達法
表示兩倍時用twice,表示三倍以上的倍數時用times。如:
The earth is 49 times the size of the moon.
This desk is twice as large as that one.
8.算式表達法:
5+6:five plus six(or five and six)
7-6:seven minus six
2×3:two multiplied by three(or two times three)
8/4:eight divided by four
9.與數詞相關的主謂一致原則
1)當名詞詞組中心詞爲表示時間、路程、金錢或重量等複數名詞時,往往根據意義一致的原則,把這些複數名詞看做一個整體,謂語採用單數形式。如:
Twenty dollars is not enough.
Two months has passed before we realized.
但是如果“數詞”單用,表示人或物,謂語動詞一般用複數。如:
Three were killed and ten were missing in that accident.
2)如果名詞詞組中心詞是“分數或百分數+of-詞組”,謂語動詞的單、複數形式取決於of-詞組中名詞或代詞的單、複數形式:如果of-詞組中名詞或代詞是單數或不可數名詞,謂語動詞用單數形式;如果of-詞組中名詞或代詞是複數,謂語動詞也用複數形式。如:
Two thirds of the earth is covered with water.
Two thirds of the people present are against the plan.
3)如果主語是many a,more than one+單數名詞構成,儘管從意義上看是複數,但謂語動詞仍用單數形式。如:
Many a student in this class has hoped a long break.
4)a+單數名詞+or two做主語,謂語動詞用單數形式。如one or two+複數名詞,謂語動詞用複數形式。如:
A word or two is missed in the sentence.
One or two words are missed in the sentence.
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