Look into hunters' eyes

    Have you ever been face to face with a cat or a sheep? If you have,you probably noticed that cats narrow their eyes to vertical (垂直的) slits (狭缝),while sheep have horizontal pupils (瞳孔).

     Why is the difference?

    Scientists from the Universities of California Berkeley and Durham in Britain may have the answer. Their research, published recently in the journal Science Advances, suggested that pupils' shapes could tell whether an animal is a hunter or gets hunted.

    The researchers took a close look at the eyes of 214 land animals.The challenge was to see if they could find a relationship between an animal's role in the food chain and the pupils' shapes.

    They found a pattern. Species with pupils that are vertical slits are more likely to be small ambush predators (捕猎者) – creatures that lie in wait for their lunch.In contrast,those with horizontal pupils are more likely to be plant-eating prey (猎物) species.

    Evolution chose the arrangement for a good reason.For hunters such as household cats,it appears that vertical pupils not only improve their ability to keep track of moving objects like mice,but also maximize (使最大化) their ability to judge the distances of the animals they hunt.

    However, an interesting discovery from the study is that the slit pupils are mostly linked to hunters that are close to the ground. Therefore, bigger cats who actively hunt down their prey, like tigers and lions, don't have slit pupils.

    On the other hand, for plant-eating prey animals, horizontal pupils give them a wider field of vision.When stretched (伸展) horizontally,the pupils allow for more light to enter from the front, back, and sides. Meanwhile, they also limit the amount of light from the sun above so the animal can see the ground better.“ Once they do find a predator,they need to see where they are running,” said leading researcher Martin Banks,a UC Berkeley professor of optometry (视光学).“They have to see well enough out of the corner of their eye to run quickly and jump over things.”

    But what happens when they bend down to eat? Researchers checked this by watching prey animals in the Oakland Zoo in California, US. They believe that when goats lower their heads to eat,their eyes rotate (旋转) to keep their pupils horizontal.

    So it seems that the eyes are indeed the window to the soul!

学会判读“气温曲线降水柱状图”是一项重要的地理技能。清你根据如图完成下题。

阅读理解

    On Monday, the Centers for Disease Control and Prevention predicted that 42% of Americans could be overweight by 2030. Our expanding waistlines lead to not only a medical problem, but according to a recent article In The New York Times, it could also endanger personal safety in some situations—in an airplane crash, for example.

    The New York Times' Christen Negroni reports that engineers and scientists are questioning whether airplane seats are adequately constructed to protect overweight travelers. Government standards for airplane seat strength（强度）— first set moe than 60 years ago — require that the seats be made for a passenger weighing 170 pounds (77kg). Today, the average American man weighs nearly 194 pounds (88kg) and the average woman 165 pounds (75kg). Negroni reports:

    “If a heavier person completely fills seat, the seat is not likely to behave as intended during a crash,” said Robert Salazar, the leading scientist at the Center for Applied Biomechanics at the University of Virginia. “The energy absorption that is built into the aircraft seat is likely to be overpowered and the passengers will not be protected properly.”

    “Nor would the injury be limited to that passenger only,” Dr. Salzar said. “If a seat or a seat belt fails,” he said, “those people who are seated nearby could be endangered from 'the uncontrolled movements of the passenger'.”

    Most complaints about airplane seats focus on their lack of comfort and high ticket price, and whether overweight passengers should be made to buy two seats. But The New York Times' article brings up another reason to feel anxious about flying. Investigators of the issue got in touch with the airplane seat and seat belt makers, but they refused to comment on the problem. Experts agreed that crash testing should be done with overweight dummies （人体模型）. Both airplane seats and seat belts should be tested, they said.

    Fortunately, however, according to Nora Marshall, a senior adviser at the National Transportation Safety Board, the board's investigators have never seen an accident involving a commercial plane in which the weight of a passenger was a problem.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

2013年的中国春节继续为低迷的世界经济环境“供暖”，让很多陷于经济危机泥潭中的国家看到了财运和希望。有媒体称，中国春节成了全世界人民的“黄金周”。这说明（    ）