英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—16

 But it's not enough. For a hunting bear, it doesn't get much worse than this. The seal could hardly fail to notice. But this battle-hardened seal is in no rush. Finally he gains some purchase, he's back in the game. He still believes he's in with a chance. He can charge at 25 miles per hour. But bears usually wait until they're 30 meters away, this one started at 300. She has all the time in the world to escape. Only the bears unexpected dunking in the ice could explain such an amateur¹ performance. 

 

The ice is now so thin. It only supports the weight of lighter² cubs³, leaving the mother struggling. This is a sign that the mother must head north to the more permanent icecap as quickly as possible. But a combination of wind and current destroys her best-laid plan. A sudden swell⁴ turns ice into open ocean. The cubs are too young to swim long distances safely.

1 amateur   

adj.业余的，非专业的；n.业余爱好者

参考例句：

• He made an amateur attempt to build a cupboard.他很外行地试做了一个碗柜。
• Although Tom's only an amateur he's a first-class player.虽然汤姆只是个业余爱好者，但却是一流的高手。

2 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

3 cubs   

n.幼小的兽，不懂规矩的年轻人( cub的名词复数 )

参考例句：

• a lioness guarding her cubs 守护幼崽的母狮
• Lion cubs depend on their mother to feed them. 狮子的幼仔依靠母狮喂养。 来自《简明英汉词典》

4 swell   

vi.膨胀，肿胀；增长，增强

参考例句：

• The waves had taken on a deep swell.海浪汹涌。
• His injured wrist began to swell.他那受伤的手腕开始肿了。