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· 听力原文（中英逐句对照）：
Pigs are notnative to North America. They were first introduced to California by Spanishand Russian explorers and settler centuries ago. In the early times, pigs wereallowed to wander freely in search of food, this practice also allowed manypigs to escape from farms and live in the wild, which became a problem.
猪并非北美本土物种。几个世纪前，西班牙和俄罗斯的探险者与定居者首次将猪引入加利福尼亚州。早期，人们允许猪自由觅食，这一做法也让许多猪从农场逃脱并在野外生存，这就成了一个问题。
In fact, as one ofthe most damaging invasive species on the continent, wild pigs cause millionsof dollars in damage every year. They also harbor diseases that threaten bothhumans and animals. Forests with wild pigs have been found to have considerablyreduced plant and animal diversity. In addition to either eating other animalsor their food supply, wild pigs damage native habitats by rooting up grassesand trambling on trees. They have also created new opportunities for invasiveplants to colonize these areas. Wild pigs will eat almost anything containingcalories. Mice, deer, birds, snakes and frogs are among their victims. They canalso harm other wild species through indirect competition, either by eating orshrinking their food supply. One particular bird species in the wild, whichplums themselves becomes an attractive food source for species of mainlandeagles. The eagles began preying on the island, and also feeding on species ofthe native fox. The native fox was wiped out completely.
事实上，作为美洲大陆破坏性最强的入侵物种之一，野猪每年造成数百万美元的损失。它们还携带会威胁人类和动物健康的疾病。有野猪出没的森林，其动植物多样性被发现大幅减少。野猪除了捕食其他动物或抢夺它们的食物外，还会通过拱食草本植物、踩踏树木来破坏本土栖息地。它们还为入侵植物在这些区域扎根创造了新机会。野猪几乎会吃任何含热量的东西，老鼠、鹿、鸟类、蛇和青蛙都在它们的捕食范围内。它们还会通过间接竞争伤害其他野生物种 —— 要么吃掉这些物种的食物，要么缩减其食物来源。野外有一种特定的鸟类，其羽毛对大陆鹰类来说成了极具吸引力的食物来源。鹰类开始在该岛屿捕食这种鸟，同时也捕食本土狐狸。最终，本土狐狸被彻底灭绝了。
· 问题（中英对照）：
16. What do we learn about early pigs in NorthAmerica?
关于北美早期的猪，我们了解到什么？
17. Why are wild pigs a threat to humans?
为什么野猪会对人类构成威胁？
18. What does the passage say about the nativefoxes on the US island?
关于美国某岛屿上的本土狐狸，文章说了什么？
