VOA慢速英语《农业报道》文本：第18课.doc

1、英语翻议讲解：这里是VOA特别英语农业报道。上周我们谈到了何时，怎样对植物进行修剪。今天，我们将讲述一下，关于为什么修剪掉植株或树木的主枝反而会长的更好的最新理解。这些发现来自两个大洲的众多科学家。加拿大卡尔加里大学的Prezemyslaw Prusinkiewicz教授带领来自英国和瑞典的科学家进行了这项研究。他们的研究结果发表在美国国家科学院院刊上。从上世纪30年代起，科学家已经得知植株活跃的生长点释放一种叫做生长素的荷尔蒙。这种荷尔蒙沿植株主干向下流动。科学家称，生长素对侧芽有间接作用，阻止植株分叉。侧芽本身也分泌生长素。研究表明，为了生长，侧芽必须能够将生长素输入主干。但是来自主干顶端

2、的生长素流动阻止侧芽的生长素流动。研究人员希望找出这种阻塞出现的原因。Prusinkiewicz教授正在澳大利亚休假，但是他给了我们一封电邮，用简单的方式让我们理解这个过程。想象一下一条交通拥挤的主道。主道上的车非常多，辅道上的车很难进入辅道。茎部就像一条拥挤的主道。新的研究表明，由于茎部非常拥挤，侧芽难以将生长素输入主干。但是，如果主干的顶端经过修剪，位于下面的其他侧芽就可以开始输送生长素，它们的生长不会再受到阻滞。来自约克郡大学的Ottoline Leyser教授表示，植株经过修剪之后，原先受到阻碍的枝条竞相增长，枝条之间的生长会受到相互之间的影响。附近的枝尖比相隔较远的枝条之间更容易相互

3、影响。Leyser表示，最强壮的枝条长势最好，无论它处于植株的哪个位置。研究发现，主枝生长最好，不是因为它的位置处于植株顶端，而是因为它最先长到那个位置。1.release n. 释放,让渡,豁免,发行的书,释放证书,版本 例句：The release of the new handgun will be subject to many political constraints. 出售这种新型手枪会收到许多政治因素的限制。vt. 释放,解放,放松,豁免,免除,发表例句：Like most true artists, it pains them to release each finished

4、 piece into other hands. 和大多数真正的艺术家一样，他们把完成的作品交给其他人是很痛心的。2.stem n. 茎,柄,船首,血统,堵塞物 例句：The stem of some plants are edible like potatoes and carrots. 一些植物的茎可以食用，比如马铃薯和胡萝卜。vi.起源于 例句：His error stemmed from carelessness. 他的错误是由于粗枝大叶而造成的。3.export v. 导出4.sabbatical a.安息日的,周期性休息的例句：He habilitated after his sa

5、bbatical at a prestigious American university. 在美国一所著名大学从事休假研究之后，他获得了资格。 5.inhibit vt.禁止,抑制例句：His embarrassment inhibited him from talking to her. 困窘使他无法和她谈话。6.affect vt.影响,妨害,感动,感染,感动;假装,冒充;常去例句：The threat of closure affected the workers morale. 工厂行将倒闭一事影响着工人的士气。1.Today we tell you about some new u

6、nderstanding of why cutting the main branch of a plant or tree can lead to better development.why引导名词性从句由关系副词when, where, why引导的定语从句 1). 基本用法定语从句除可用关系代词引导外，还可用关系副词when, where与why来引导，它们的区别是：when用于指时间，where用于指地点，why用于指原因。when, where, why 在定语从句中均用作状语。如：1980 was the year when he was born. 1980是他的出生年。Thi

7、s is the town where I was born. 这就是我出生的城市。This is the town where I was /SPAN> These are the reasons why we do it. 这些就是我们这样做的理由。2). 先行词问题关系副词when关系副词宋体>和where的先行词是表示时间(如the day, the days, the time, the year等)和地点(如the place, the house, the factory, the station等)的一类词，而关系副词why的先行词通常只是whythe reason

8、(s)。另外，when和where可引导限制性和非限制性定语从句，而why则只用于引导限制性定语从句，不用于引导非限制性定语从句。3). 一点注意注意不要以为在时间名词后就一定用关系副词when，在地点名词后就一定用关系副词 where，在表示原因的the reason后就一定用关系副词why。到底选用关系副词还是关系代词，关键是看它们在定语是用作状语(用关系副词)还是用作主语或宾语(用关系代词)。如：Dont forget the time (that) Ive told you. 不要忘记我告诉你的时间。(that用作told的宾语)Ill never forget the days wh

9、en I worked with you. 我永远不会忘记我与你共事的日子。(when用作状语)He works in a factory that which makes radio parts. 他在一家制造无线电零件的工厂工作。(that, which 在从句中用作主语，且不能省略)He works in the factory where his father worked. 他在他父亲工作过的那家工厂工作。(where作状语)Thats the reason that which he explained to us. 那就是他向我们解释的理由。(that或which在从句中用作ex

10、plained的宾语) Thats the reason why she left home. 那就是她离家出走的原因。(where在从句中作状语)4). 一个错点英语中的关系副词主要是 when, where, why三个。不要想当然地将how用作关系副词修饰the way。如不说 This is the way how he spoke，可改为 This is the way how he spoke This is how he spoke(how引导的是表语从句)，当然也可说成 This is the way (that, in which) he spoke.(其中的that, in

11、 which可省略) 2.Scientists say the auxin has an indirect effect on buds on the side of the stem to prevent branching.have effect on对.有影响例句：Some drugs have a deleterious effect on the body. 有些药品对身体有害。3.So many cars are on the main road that the cars on the side roads cannot enter.So that的意思是“如此地以致于”，它引导

12、结果状语从句。在口语中，sothat的that常被省去。例：She felt so sad that tears came to her eyes她非常悲伤，泪水盈眶。John was so drunk（that）he could not stand still约翰醉得站也站不住了。He spoke so rapidly（that）we could hardly follow him他说得很快，我们很难听清楚他在说什么。4.They are no longer inhibited from growing.no longer不再，已不 例句：They were trying to put on

13、e over on us and they would no longer get away with it. 他们总是想花言巧语地骗我们，但是他们以后休想再得逞了。5.The study found that the main shoot grows the best of all not because of its position at the top of the plant, but mostly because it got there first.not but不（是）而（是）They were not the bones of an animal, but of a huma

14、n being! 他们不是动物的骨头，而是人的骨头。 另外一个结构类似但是意思不同的用法：Its not that but不是因为而是因为这是一个对称句型，表示不是因为.而是因为.才干什么。 支持范例 1). Its not that I dont like the car, but I think it is too expensive. 不是我不喜欢这辆车，而是它太贵了。 2). Its not that I am unwilling to help you, but Im tied up with extra work these days. 不是我不愿意帮你，而是因为这段时间我工作太忙

15、了。 3). Its not that he doesnt need your help, but he thinks it will be an inconvenience to you. 不是他不需要你帮忙，而是他怕给你带来麻烦。 英语听力原文：This is the VOA Special English Agriculture Report.img talked last week about when and how to prune plants. Today we tell you about some new understanding of why cutting the m

16、ain branch of a plant or tree can lead to better development.The findings are from researchers on two continents. Professor Prezemyslaw Prusinkiewicz of the University of Calgary in Canada led the research with scientists from Britain and Sweden. Their study appears in the Proceedings of the Nationa

17、l Academy of Sciences.Researchers have known since the nineteen thirties that the actively growing tip of a plant releases a hormone called auxin. This hormone flows down the main stem. Scientists say the auxin has an indirect effect on buds on the side of the stem to prevent branching.These buds th

18、emselves also produce auxin. The research suggests that to grow, they have to be able to export the hormone into the main stem. But the flow from the stem tip prevents them from doing this. The researchers wanted to find out how this blocking happens.Professor Prusinkiewicz is on sabbatical leave in

19、 Australia, but he sent us an e-mail suggesting a simple way to understand the process. Think of a major road crowded with traffic. So many cars are on the main road that the cars on the side roads cannot enter.The stem is like the crowded main road. The new research shows that the buds on the side

20、cannot export their auxin into the main stem because it is too full. But if that main shoot is pruned, other buds below it can start exporting. They are no longer inhibited from growing.Ottoline Leyser from the University of York says that after a plant is pruned, all the inhibited shoot tips compet

21、e with each other to grow. In doing this, the branches influence each others growth. Nearby shoot tips are more likely to affect each other than those that are far apart from each other.Professor Leyser says the strongest branches grow best, wherever they may be on the plant. The study found that th

22、e main shoot grows the best of all not because of its position at the top of the plant, but mostly because it got there first.And thats the VOA Special English Agriculture Report, written by Jerilyn Watson. Transcripts and MP3s of our reports, including last weeks advice about pruning, can be found at . You can also post comments. We invite you to share your own experiences - good or bad - with pruning plants and trees. Im Steve Ember.