1.You use for when you state or explain the purpose of an object, action, or activity. 为了 (表示目的、用途)例:...drug users who use unsterile equipment for injections of drugs.…用未消过毒的器具注射毒品的吸毒者们。The knife for cutting sausage was sitting in the sink.用于切香肠的刀在水槽里。2. You use for after nouns expressing reason or cause. 因为 (作介词,用于表示原因的名词后)例:He's soon to make a speech explaining his reasons for going.他很快将会发表讲话说明去的原因。The county hospital could find no physical cause for Sumner's problems.县医院查不出萨姆纳的问题的生理原因。3. If something is for sale, hire, or use, it is available to be sold, hired, or used. 供 (销售、租用、使用)例:Freshwater fish for sale.供出售的淡水鱼。...a room for rent.…一间供租用的房间。4. If you do something for a particular occasion, you do it on that occasion or to celebrate that occasion. 为 (某场合)例:He asked his daughter what she would like for her birthday.他问他女儿想要如何过她的生日。5.If you leave for a particular place or if you take a bus, train, plane, or boat for a place, you are going there. 前往 (某地)例:They would be leaving for Rio early the next morning.他们次日一早将前往里约。 BEFORE NUMBERS, AMOUNTS, AND TIMESfor 1. You use for to say how long something lasts or continues. 用于表示持续的时间例:The toaster was on for more than an hour.烤箱开了一个多小时。They talked for a bit.他们谈了会儿。2. You use for to say how far something extends. 用于表示延伸的距离例:We drove on for a few miles.我们继续开了几英里。3. If something is bought, sold, or done for a particular amount of money, that amount of money is its price. 以 (某数量的钱)例:We got the bus back to Tange for 30 cents.我们以30美分乘公共汽车回到了坦格。The Martins sold their house for about 1.4 million dollars.马丁一家以约一百四十万美元把他们的房子卖了。4. If something is planned for a particular time, it is planned to happen then. 于 (某时间)例:...the Baltimore Boat Show, planned for January 21 – 29.…计划于1月21至29日举行的巴尔的摩船展。The designer will be unveiling her latest fashions for autumn and winter.该设计师将公布她的最新款秋冬时装。5. You use expressions such as for the first time and for the last time when you are talking about how often something has happened before. 首次/最后一次例:He was married for the second time.他第二次结婚了。6. You use for when you say that an aspect of something or someone is surprising in relation to other aspects of them. 对…来说例:He was tall for an eight-year-old.对一个8岁的孩子来说他长得很高。7.You use for with "every" when you are stating a ratio, to introduce one of the things in the ratio. 对于 (与every连用,用于引出比率中之一)例:For every farm job that is lost, two or three other jobs in the area are put at risk.对于失去的每份农场工作,该地区的其它两三个工作就会被置于危险中。8.You can use for in expressions such as dollar for dollar or mile for mile when you are making comparisons between the values or qualities of different things. 对应 (用于比较不同事物间的价值或品质)例:...the Antarctic, mile for mile one of the planet's most lifeless areas.…每英里都是地球上最无生命的地区之一的南极洲