英语听力：自然百科 冰冻星球 前往地球尽头—10

 The bison/ form a defensive¹ circle around their young, horns pointing outwards².

 

The wolves need the bison to break rank, but the tables are turning and now the wolves have to retreat. The pack focus their attention on the rear of the herd³ and the bison/ begin to panic. 

 

A young bison falls behind. Even this yelling dwarfs⁴ the wolves. Running head down, the herd's only thought is to escape, a stroke of luck for the wolves. The kill will feed the pack for several days but then they will have to resume the chase. At the frozen ends of our planet the struggle for survival never eases. South of the tree line, the winters are shorter, so trees grow faster and taller and forests begin to appear.

1 defensive   

adj.防御的；防卫的；防守的

参考例句：

• Their questions about the money put her on the defensive.他们问到钱的问题，使她警觉起来。
• The Government hastily organized defensive measures against the raids.政府急忙布置了防卫措施抵御空袭。

2 outwards   

adj.外面的，公开的，向外的；adv.向外；n.外形

参考例句：

• Does this door open inwards or outwards?这门朝里开还是朝外开？
• In lapping up a fur,they always put the inner side outwards.卷毛皮时，他们总是让内层朝外。

3 herd   

n.兽群，牧群；vt.使集中，把…赶在一起

参考例句：

• She drove the herd of cattle through the wilderness.她赶着牛群穿过荒野。
• He had no opinions of his own but simply follow the herd.他从无主见，只是人云亦云。

4 dwarfs   

n.侏儒，矮子（dwarf的复数形式）vt.（使）显得矮小（dwarf的第三人称单数形式）

参考例句：

• Shakespeare dwarfs other dramatists. 莎士比亚使其他剧作家相形见绌。 来自《简明英汉词典》
• The new building dwarfs all the other buildings in the town. 新大楼使城里所有其他建筑物都显得矮小了。 来自辞典例句