题型:阅读理解 题类:常考题 难易度:普通
山东省烟台市2019-2020学年高二下学期英语期末考试试卷
Cara Clarkson and her family were overjoyed when spotting two young grizzly bears (灰熊) — one with rarely seen all-white fur, alongside the Trans-Canada Highway.
“White grizzly bears are unheard of, so it was a luxury and incredible experience,” said Cara, sharing her images and videos on social media and saying that was a real treat given that the family was out celebrating her husband's and son's birthdays. Mike Gibeau, an animal specialist, said the Clarksons who encountered the white bear — now called Nakoda, are truly lucky, for white grizzly bears are incredibly rare.
The expert doesn't believe the grizzly's white fur is a case of albinism, a disorder in which an animal fails to produce melanin, which is responsible for skin, hair, and eye color. Instead, he thinks the bear's unusual coloring is the result of a recessive (隐性) gene (基因), the characteristics of which are often covered by those of dominant genes. However, if both parents carry the same recessive gene — in this case, one that results in white fur — it can be passed on to latergenerations.
Though this is the first time the world has seen the white grizzly, park officials, who have known of Nakoda's existence since 2018, never publicized the unique bear due to fear that it would be heartlessly run after by fans eager to see these unusual-looking animals.
As it turns out, they were right. Nakoda's photos and videos, which have gone viral, have led to crowds of people rushing to the bear's current location, resulting in unsafe parking and traffic jams. The concerned officials enforced a 10-kilometer no-stopping zone, which they hope will inform visitors to travel through the area safely and to prevent these bears from getting hit on the highway.
Wildlife experts, who are trying to lead the young grizzlies away from the highway, hope to help them develop a behavior of avoidance of humans and eventually head to the forests, where they can live a long, healthy life.
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