本试题 “_____ of the students in our class _____ money to the quake-hit areas these days.[ ]A. Two third; have raisedB. Two thirds; has raisedC. Two three;...” 主要考查您对分数
现在完成时
等考点的理解。关于这些考点您可以点击下面的选项卡查看详细档案。
英语分数的表示法:
一、用“基数词+序数词”表示
1.分数在英语中通常是借助于基数词和序数词来共同表达的。其中基数词表示分子,序数词表示分母。
如:
The centimeter is one-tenth of the decimeter or one-hundredth of the meter.厘米是分米的十分之一,或者说是米的百分之一。
However,the number of boys will bea third or less than the girls in the class.但是,班里男生的人数将比女生少三分之一或更少。
从以上例子可以看出:
①分子除用one外,也可用a;
②如果分子大于1,分母要用复数形式。但是,1/2不能说a(one)second,而要说a(one)half。例如:
The sum of one half,one third and one fourth of a certain number is 13.某数的1/2,1/3和1/4的和是13。
1/4 和3/4可以说a(one)fourth和three fourths,但常用a quarter和three quarters表示。
③应该注意的是,分数修饰名词时,若该名词是不可数名词只能用单数;
④若是可数名词,用单数或复数均可。但是,若它们在句子中作主语,则谓语动词是用单数还是复数取决于名词,即与分数所修饰的名词保持一致。例如:
Only one-fifth of air consists of oxygen.氧气只占空气的1/5。
About two thirds of the students attendthe meeting.大约2/3的学生都参加了会议。
2.带分数也是常见的英语数词表达。所谓带分数,实际上是“整数+分数”,表达时分而述之,只是整数部分与分数部分要用连词and连接。
当带分数修饰名词时,该名词通常是复数,但若名词置于整数one或a之后,则用单数。
“带分数+名词”作主语时,谓语动词根据临近原则要用复数。例如:
You should finish the work within one and a fourth hours.你应在1.25小时内完成工作。
The atom breaks up in a minute and a quarter.原子在1.25分钟内裂变。
二、用percent等表示
表示百分之一可以说one(a)hundredth,但更常用one percent或percent,即用百分数表示法来表达。例如:
Our bodies are 65percent water.我们人体含65%水分。
Seventy-five percent of the earth'ssur- face is covered by water.地球表面的75%被水覆盖着。
Eighty-five percent of the students in English department are girls.英语系85%的学生是女生。
三、用part表示
名词part有“……分之一”的意思,分子大于1时,part用复数。表示分数的结构一般有以下三种:
1.“基数词(或a)+序数词+part(s)” a hundred part百分之一
2.“基数词+part(s)+in+基数词” five parts in one thousand千分之五
3.“基数词+part(s)+per+基数词” one part per million百万分之一
四、用“基数词+介词+基数词”表示
借助介词表示分数,介词前的数词是分子,介词后的数词是分母。例如:
1.Ninety- nine people out of a hundred,if they were asked who first found America,would answer Clumbus.
如果要问是谁首先发现美洲,一百个人中有九十九个(百分之九十九)将回答是哥伦布。
这种结构中的介词主要有in,out of,of 以及to
2.The map is drawn to a scale of one of ten thousand.
这张地图是按万分之一的比例绘制的。
数字 |
表示法 |
6% |
six percent |
0.58% |
(naught) point five eight percent |
200% |
two hundred percent |
现在完成时的用法:
1.表示动作发生在过去某个不确定的时间,但对现在留下了某种影响和结果。常被just、already、yet 等副词修饰。如:
-Have you had lunch yet?
-Yes,I have. I've just had it.
2.表示从过去某一时刻开始一直持续到现在的动作或状态。这个动作可能刚停止,可能仍然在进行。
常带有for和since等表示一段时间的状语。如:
He has taught here since 1981
他自1981年就在这儿教书。(可能还要继续教)
I have't seen her for four years.
我有四年没见到她了。
3.表示说话前发生过一次或多次的动作,现在成为一种经验,一般译为汉语“过”。
常与twice,ever,never,three times等时间状语。 如:
I have been to Beijing twice.我去过北京
4. 现在完成时还往往可以同包括现在时间在内的时间状语连用,如:
now,up to these few days/weeks/months/years,this morning/week/month/year,just,today,up to present,so far等:
Peter has written six papers so far.
Man has now learned to release energy from the nucleus of the atom.
There has been too much rain in San Francisco this year.
The friendly relations and cooperation between our two countries have been enhanced in the past few years.
Up to the present everything has been successful.
5.现在完成时往往同表示不确定的过去时间状语连用,如:
already(肯定),yet(否定,疑问),just,before,recently,still,lately,never等:
He has already obtained a scholarship.
I haven't seen much of him recently (lately).
We have seen that film before.
Have they found the missing child yet?
6.现在完成时的"完成用法"
现在完成时的"完成用法"指的是动作发生在过去某一时刻并已结束,但该动作对现在产生了影响,与现在情况具有因果关系。
例如:
He has turned off the light.他已把灯关了。(动作结束于过去,但说明的是现在的情况--灯现在不亮了。)
现在完成时"完成用法"的特点是动作不延续,因此:
该时态只能与表示不定的过去时间状语(如:already,yet,before,recently等)、频度时间状语(如:never,ever,once等)、包括现在时刻在内的时间状语(如:this morning / month /year...,today等)连用。
例如:Have you found your pen yet?你已找到你的钢笔了吗?
7.现在完成时的"未完成用法"
现在完成时的"未完成用法"指的是动作开始于过去某一时刻,一直延续到现在,或可能还要继续下去。
例如:
He has lived here since 1978.自从1978年以来,他一直住在这儿。
(动作起始于1978年,一直住到现在,可能还要继续住下去。)
I have been in the army for more than 5 years.我在部队已经呆了五年多了。
(动作开始于5年前,一直延续至今,有可能还要继续下去。)
此种用法的句中常需一个表示一段时间的状语(由since或for引导),或表示与现在时刻相连的时间状语(如:up to now,so far)等。
例如:
I have heard nothing from him up to now.到目前为止我没有他的任何消息。
注意:现在完成时的未完成用法只适用于延续性动词,不可用于终止性动词,即瞬间完成或延续时间很短的动词。
如:come,go,arrive,leave,join,become,die等。
8.一段时间+has passed+since从句
主语+have / has been+since短语
例如:He has been in the League for three years.
或It is three years since he joined the League. 他入团已三年了
9. 现在完成时常和短语 "up to now /till now","so far" (意思是从过去某一确定的时间一直延续到现在)连用。
Up to/till now he's read many story books. 至今他已读过好多故事书。
I've been to New York three times so far. 至今我已到纽约去过三次。
has gone (to),has been (to),has been (in) 的区别
has gone to:去了没回
has been to :去过
has been in:呆了很久
与“_____ of the students in our class _____ money to the qua...”考查相似的试题有: