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by的所有用法归纳

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点拨by所有的用法归纳

by表单位的用法归纳

表示单位,意为“以……计”,其后通常接表示计量单位的单数名词,且名词前要用定冠词。如:

They are paid by the hour (by the month). 他们所得报酬按小时(月)计。

Milk is sold by the pint, butter by the pound, and eggs by the dozen. 牛奶按品脱卖,黄油论磅卖,蛋类论打卖。

有时也接抽象名词,此时通常不用冠词。如:

Bananas are usually sold by weight. 香蕉通常按重量卖。

 by表示时间的用法

表示时间,指“最迟在……之前”“到……的时候已经”,此时要注意它所连用的时态。如:

He was very tired by the evening. 他到晚上已经很累了。

He has read about 40 pages of the book by now. 现在这本书他已读了大约40页。

We will have finished the work by next month. 到下个月我们就会干完了这工作。

By the time the doctor arrived the patient had died. 在医生到达时,病人已经死了。

另外,表示时间时,它还可表示“在……期间”,通常连用的名词是 day, night, moonlight, daylight等,注意名词前通常不用冠词。如:

Cats sleep by day and hunt by night. 猫白天睡觉,夜里捉老鼠。

Do you like to swim by moonlight? 你喜欢在月光下游泳吗?

表示手段或方式等,注意以下用法:

(1) 表示“乘”“坐”时,其后接交通工具(如 bus, bike, train, plane, car, taxi, ship等)或与交通工具密切相关的名词(如air, water, land, road等),在句中主要用作方式状语,其中通常不用冠词或其他限定词。如:

They came here by the first bus. 他们是坐第一班车来的。

但是,若表示交通工具的名词前插有定语修饰语,则也可以用冠词。如:

We’re going by the 9:30 train. 我们坐9:30的火车去。

We went to Shanghai by a large ship. 我们乘一艘大船去上海。

注意,汉语说“步行”,英语习惯上用on foot, 而不用 by foot。

(2) 注意以下表示方式的有用表达,其中不用冠词或其他限定词:

by phone 用电话            by telegram 用电报
by letter 用信件             by express 用快件
by air mail 用航空邮件      by ordinary mail 用平信
by post 用邮寄              by radio 用无线电
by hand 用手工             by machine 用机器
注意下面两例用by与用with的区别:

The letter was written by hand. 这封信是用手写的(即不是打印的)。(by hand表示一种抽象的手段,是无形的,注意其中没用冠词或其他限定词)

I write with my hand, but he writes with his mouth. 我用手写字,但他却用嘴写字。(with one’s hand表示一种具体的工具,是有形的,注意其中用了物主代词)

(3) 后接动名词表示行为的方式或手段,这是一种常用表达。如:

He makes a living by teaching. 他以教书为生。

Lock this door by turning the key twice to the left. 锁这扇门要把钥匙向左转两圈。
 

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