英语听力：自然百科 大迁徙 Great Migrations—17

 The merciless yellow crazy ants take a terrible toll¹. But by sheer force of numbers and the inexorable will of their genes², they prevail. 

 

That is the fierce logic³ of migrations⁴. But what is logical for the many can be madness for the few.

 

At the Mara River, the madness has begun. The crocodiles, from long experience, know who to target--the young. Calves⁵ strain to stay by their mother sides to no avail. Powerful sharp hooves descend⁶ on the reptiles⁷ again and again. On the far banks, wrenching⁸ scenes of those who almost made it, watched helpless by distraught mothers.

1 toll   

n.过路(桥)费；损失，伤亡人数；v.敲(钟)

参考例句：

• The hailstone took a heavy toll of the crops in our village last night.昨晚那场冰雹损坏了我们村的庄稼。
• The war took a heavy toll of human life.这次战争夺去了许多人的生命。

2 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

3 logic   

n.逻辑(学)；逻辑性

参考例句：

• What sort of logic is that?这是什么逻辑？
• I don't follow the logic of your argument.我不明白你的论点逻辑性何在。

4 migrations   

n.迁移，移居( migration的名词复数 )

参考例句：

• It foundered during the turmoils accompanying the Great Migrations. 它在随着民族大迁徙而出现的混乱中崩溃。 来自辞典例句
• Birds also have built-in timepieces which send them off on fall and spring migrations. 鸟类也有天生的时间感应器指导它们秋春迁移。 来自互联网

5 calves   

n.(calf的复数)笨拙的男子，腓；腿肚子( calf的名词复数 )；牛犊；腓；小腿肚v.生小牛( calve的第三人称单数 )；（冰川）崩解；生（小牛等），产（犊）；使（冰川）崩解

参考例句：

• a cow suckling her calves 给小牛吃奶的母牛
• The calves are grazed intensively during their first season. 小牛在生长的第一季里集中喂养。 来自《简明英汉词典》

6 descend   

vt./vi.传下来，下来，下降

参考例句：

• I hope the grace of God would descend on me.我期望上帝的恩惠。
• We're not going to descend to such methods.我们不会沦落到使用这种手段。

7 reptiles   

n.爬行动物，爬虫( reptile的名词复数 )

参考例句：

• Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
• Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》

8 wrenching   

n.修截苗根，苗木铲根（铲根时苗木不起土或部分起土）v.（猛力地）扭( wrench的现在分词 )；扭伤；使感到痛苦；使悲痛

参考例句：

• China has been through a wrenching series of changes and experiments. 中国经历了一系列艰苦的变革和试验。 来自辞典例句
• A cold gust swept across her exposed breast, wrenching her back to reality. 一股寒气打击她的敞开的胸膛，把她从梦幻的境地中带了回来。 来自汉英文学 - 家（1-26） - 家（1-26）