[新东方背诵文选80篇：44从冰山中获取淡水ObtainingFre]44 Obtaining Fresh Water from Icebergs The concept of obtaining fresh water from icebergs that are towed to populated areas and arid regions of the world was on...+阅读
58 Animals' passes
Researchers he found that migrating animals use a variety of inner passes to help them nigate. Some steer by the position of the Sun. Others nigate by the stars. Some use the Sun as their guide during the day and then switch to star nigation by night. One study shows that the homing pigeon uses the Earth's magic fields as a guide in finding its way home and there are indications that various other animals from insects to mollusks, can also make use of magic passes. It is of course very useful for a migrating bird to be able to switch to a magic pass when clouds cover the Sun; otherwise it would just he to land and wait for the Sun to e out again.
Even with the Sun or stars to steer by, the problems of nigation are more plicated than they might seem at first. For example, a worker honeybee that has found a rich source of nectar and pollen flies rapidly home to the hive to report. A naturalist has discovered that the bee scout delivers her report through a plicated dance in the hive, in which she tells the other workers not only how far away the food is, but also what direction to fly in relation to the Sun. But the Sun does not stay in one place all day. As the workers start out to gather the food, the Sun may already he changed its position in the sky somewhat. In later trips during the day, the Sun will seem to move farther and farther toward the west. Yet the worker bees seem to he no trouble at all in finding the food source. Their inner clocks tell them just where the Sun will be and they change their course correspondingly.
动物的罗盘
研究人员已经发现迁徙性动物可以借助各种各样的体内罗盘来校正方向。 有些动物借助太阳的位置辨别方向，有些则依靠星星。 还有的白天利用太阳，晚上利用星星。 有研究发现信鸽以地磁场为向导来找到回家的路。 还有迹象表明许许多多其它生物，从昆虫到软体动物，也能利用这种磁场罗盘。 具有这种磁场罗盘，对候鸟来说当然非常有用，因为如果乌云遮日，它可以以磁场为向导继续飞行，否则它就只好着陆，等待太阳重新出现。 即使是借助太阳或星星导航，其中的学问也比它表面看起来的要复杂得多。 例如，一只工蜂找到了花圃蜜园，急忙飞回蜂房报信。博物学家发现这只蜂探在蜂房里跳了一段极为复杂的舞，通过这段舞她不但告诉其它工蜂食物有多远，而且报告了以太阳为参照的飞行路线。 但太阳不会呆在天上不动。 当蜂群出发采食时，太阳可能已经多少改变了它在天空中的位置。 出发得越迟，太阳就越偏西，可这似乎没给寻找食物源的工蜂们带来任何不便。 它们体内的时钟告诉他们太阳应在的位置，据此它们相应地改变前进的方向。
以下为关联文档：
新东方背诵文选80篇：55创造颜色CreatingColors55 Creating Colors There are two ways to create colors in a photograph. One method, called additive, starts with three basic colors and adds them together to pr...
新东方背诵文选80篇：46视觉Vision46 Vision Human vision like that of other primates has evolved in an arboreal environment. In the dense plex world of a tropical forest, it is more important to...
新东方背诵文选80篇：11考古学Archaeology11 Archaeology Archaeology is a source of history, not just a humble auxiliary discipline. Archaeological data are historical documents in their own right, not...
新东方背诵文选80篇：08美国革命AmericanRevolution08 American Revolution The American Revolution was not a revolution in the sense of a radical or total change. It was not a sudden and violent overturning of th...
新东方背诵文选80篇：48细菌Bacteria48 Bacteria Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micr...
新东方老师谈句型的灵活运用句子也是如此，我们提倡简炼，但不是说都用简单句。有人认为在写作考试中，采用简单句、短句、容易掌握，不在会出错，因而也最保险。这话没有错，但简单句用得太多，造成简单句的堆彻实际...
新东方背诵文选80篇：73显微技术TheMicroscopicTechni73 The Microscopic Technique Each advance in microscopic technique has provided scientists with new perspectives on the function of living anisms and the nature...
新东方名师谈考研英语完形填空的复习方法考研的完形填空往往被很多考生所忽视，特别是在临考之前的时候。但事实上，考研完形如果复习的好，其收获绝对不只是那20道题目10分。对于完形的复习，分为以下几个方面： 首先是词汇...
新东方靳萌点评2008考研翻译本次考试试题来源于Mayo W. Hazeltine所写的一篇学术评论，主题是关于达尔文在现代科学中的地位。 In his autobiography，Darwin himself speaks of his intellectual powers w...
