归纳如下：1. 在被动语态里表示动作的执行者或施动者，意思为\"由......；被......\"。例如：This prizewinning essay was written by an unknown author。这篇获奖文章是由一位名不见经传的作家写的。 The village is surrounded by a lot of tall trees. 这个村庄被许多大树所环绕。 2. 表示期限，意思为\"到......为止；不迟于......；在......之前\"。例如：The plane will surely arrive by ten o\'clock.飞机十点钟一定会到达。 We hope we can complete our task by twelve. 我们希望到十二点钟能够完成任务。By the end of last month, he had collected over 500 stamps. 3. 表示空间位置，意思为\"在......旁边；靠近......\"，相当于near, beside, next to。例如： There is a desk by the window. 窗子旁有一张办公桌。 The woman is washing the clothes by the well.那位妇女在井旁边洗衣服。 4. 表示通讯方式，意为\"用......\"，by 后面的名词不带冠词，也不用复数形式。例如：She told me the good news by phone. 她打电话把这个好消息告诉我。 That university informed me of my acceptance by letter. 那所大学用书信通知我，我被录取了。 5. 表示交通方式，意思为\"乘......；坐......\"，后接单数名词，不带冠词。例如：They have decided to go to Macau by plane. 他们已决定乘飞机去澳门6. 表示方式、手段，意思是\"借助；凭......\"， 后接名词或动名词。例如：He passed the college entrance examination by hard work. 他凭着勤奋通过了高考。 The woman makes a living by selling newspapers. 那个妇女靠卖报谋生。 7. 表示程度和比率，通常指时间、空间和数量等的相差。例如：He is older than his wife by three years. 他比他妻子大三岁。 The car factory hopes to increase its output by 50% next year. 这家汽车制造厂希望明年将汽车产量提高百分之五十。With modern technology, production cost has dropped by one half. 由于采用了现代技术，劳动成本下降了一半。8. 表示计酬或销售方式等，意思为\"按 ......计算；以......为单位.例如：Cleaning women in big cities usually get paid by the hour.大城市的清洁女工通常按小时付给报酬。 Translation is paid by the word. 译稿是以字数计酬的。 They sell the cloth by the yard. 他们按码售布。The eggs are sold by the dozen. 这些鸡蛋按打出售。 9. 表示面积或体积的计算方式，意思为"用......去乘"。例如： The room measures fifteen feet by twenty feet. 这房间十五英尺宽二十英尺长。 10. 表示\"根据......；按照......\"。例如：You shouldn\'t judge a person by (his) appearance. 你不该以貌取人。 We must play the game by rule.我们必须按照规则进行比赛。 11. by hand表示\"用手的；手工制的；专人送的例如：These baskets are made by hand. 这些篮子是手工做的This letter was delivered by hand. 这封信是由专人送来的。 12. 表示"就......而言；关于......"。例如：He is a good writer, although he is not a writer by profession.
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