[解析]
(1)C.推理判断题。根据第一段Killer whales,or orcas,are known for their severe attacks on sea animals but they have never posed a threat to humans.However,since late July,the normally social animals have been intentionally attacking sailboats off the coasts of Spain and Portugal.(虎鲸,以其对海洋动物的严重攻击而闻名,但它们从未对人类构成威胁。然而,自7月下旬以来,这些通常群居的动物一直在西班牙和葡萄牙沿海蓄意攻击帆船。)可知,虎鲸改变了他们的行为,故选C。
(2)C.细节理解题。根据第三段Some believe it could be a result of the overfishing of the bluefish tuna﹣the orcas' primary food source﹣which has left the areas' killer whales starving(饥饿)and unable to feed their babies. "I saw them look at boats carrying fish.I think they know humans are somehow related to food shortages," says Ken Balcomb,senior scientist at the Center for Whale Research in Washington,USA.(一些人认为,这可能是由于过度捕捞蓝鱼金枪鱼的结果,蓝鱼金枪鱼是虎鲸的主要食物来源,导致该地区的虎鲸挨饿,无法喂养它们的宝宝。我看见他们看着载鱼的船。我想他们知道人类与食物短缺有某种联系,美国华盛顿鲸鱼研究中心的资深科学家Ken Balcomb说。)可知,Ken Balcomb认为是虎鲸的食物短缺导致了这些事件,故选C。
(3)D.词义猜测题。根据第三段The environmentalists believe the sudden increase in boat traffic and fishing activities,after months of absence due to restrictions on human activity last spring,could also be contributing to the agitation.(环境学家认为好几个月的春季禁渔期结束,渔船流量突然增加和捕鱼活动也可能会导致这些虎鲸袭击渔船事件。)该句分析了另一个引发虎鲸袭击事件的原因,据此可以推测划线词的意思是虎鲸袭击事件。结合选项:A.Human activities人类活动。B.Food shortages食物缺乏。C.The overfishing过度捕捞;D.The attacks袭击。故选D。
(4)D.标题归纳题。根据第一段Killer whales,or orcas,are known for their severe attacks on sea animals but they have never posed a threat to humans.However,since late July,the normally social animals have been intentionally attacking sailboats off the coasts of Spain and Portugal.(虎鲸,以其对海洋动物的严重攻击而闻名,但它们从未对人类构成威胁。然而,自7月下旬以来,这些通常群居的动物一直在西班牙和葡萄牙沿海蓄意攻击帆船。)可知,文章开头介绍虎鲸袭击渔船的异常行为。接下来分析各种有可能引发虎鲸异常行为的诱因,所以题目应该是:虎鲸为什么袭击渔船。结合选项:A.How do killer whales attack humans?虎鲸是如何攻击人类的;B.Why are boats banned from sailing on the sea?为什么禁止船只在海上航行;C.How can we live in harmony with animals?我们如何与动物和谐相处;D.Why Are Killer Whales attacking Boats?为什么虎鲸会攻击船只。故选D。