概要:ersity in Ithaca, New York, agrees. "We really need to know elephant numbers and the evidence that we have is quite indirect," says Payne, who electronically tracks elephants.Counting elephants from planes is impossible in the vast rainforests of Central Africa. So researchers often estimate elephant numbers by counting dung piles in a given area. They also need to know the rate at which dung decays: Because it's extremely difficult to determine these rates, however, researchers counting elephants in one region
2017职称英语考试模拟训练:综合类A考试试题及答案,http://www.jdxx5.comThe mistake could lead researchers to think that there are twice as many elephants as there really are in some regions, according to Andrew Plumptre of the Wildlife Conservation Society (WCS) in New York.
Biologist Katy Payne of Cornell University in Ithaca, New York, agrees. "We really need to know elephant numbers and the evidence that we have is quite indirect," says Payne, who electronically tracks elephants.
Counting elephants from planes is impossible in the vast rainforests of Central Africa. So researchers often estimate elephant numbers by counting dung piles in a given area. They also need to know the rate at which dung decays: Because it's extremely difficult to determine these rates, however, researchers counting elephants in one region tend to rely on standard decay rates established elsewhere.
But researchers at the WCS have found that this decay rate varies from region to region depending on the climate and environment. Using the wrong values can lead the census astray (离开正道), says Plumptre.
He and his colleague Anthony Chifu Nchanji studied decaying elephant dung in the forests of Cameroon. They found that the dung decayed between 55 and 65 per cent
more slowly than the dung in the rainforests of neighbouring Gabon. If researchers use decay rates from Gabon to count elephants in Cameroon, they would probably find more elephants than are actually around.
This could mean estimates in Cameroon are at least twice as high as those derived from decay rates calculated locally, says Plumptre. "However accurate your dung density estimate might be, the decay rate can severely affect the result."
Plumptre also says that the dung-pile census should be carried out over a region similar in size to an elephant's natural range. The usual technique of monitoring only small, protected areas distorts numbers because elephants move in and out of these regions, he says. "If the elephant population increases within the protected area, you can not determine whether it is a real increase or whether it is due to elephants moving in because they are being poached (入侵偷猎) outside."
Plumptre says that similar problems may also affect other animal census studies that rely on indirect evidence such as nests, tracks or burrows (地洞).
6 The word "threatened" in the first sentence of the first paragraph could be best replaced by
A "endangered".
B "frightened".
C "killed".
D "angered".
7 Why do researchers estimate elephant numbers in an area by counting dung piles?
A Because elephants are difficult to catch.
B Because it is not possible to count elephants from a plane.
C Because it is not possible to keep track of elephants.
D Because elephants are shy animals.
8 Piles of dung can't be relied upon when it comes to estimating elephant numbers because
A they are different in size.
B they scatter all over the region.
C they are different in decay rate.
D they are different in quality.
9 According to Plumptre, the region over which a dung-pile census is carried out should be
A small enough.
B well protected.
C carefully monitored.
D large enough.
10 The first word "He" in paragraph 6 refers to
A Andrew Plumptre.
B Katy Payne.
C Anthony Chifu Nchanji.
D the writer of the article.
第三篇
More Than Just Money
When Patricia Rochester decided to go back to school after ten years as a staff nurse at Toronto Western Hospital, her employer not only cheered her on, but also paid her tuition and gave her a day off with pay every week to study. Throughout her years at the hospital, Rochester has also taken workshops on everything from coaching peers to career development D courses that she believes have helped her advance at work. "I'm now head of the mentoring (指导) program for new hires, students and staff nurses," she says. "There's a lot of room for personal improvement here."
Perhaps as important, Rochester says her employer supports and values her work.
"If you put in overtime," the nurse points out, "you get your meals —— they'll order in pizza or Greek food or Chinese." And if staffers feel stiff and stressed from too many hours on the ward, they can call for a free 15-minute shoulder-and-neck massage (按摩) or even sign up for an eight-week evening course on meditation skills and stress-relief. If that's not enough, employees can take advantage of five family days a year that can be used if the kids come down with the flu or an aging parent needs ferrying to an important doctor's appointment. And they have access to a range of perks (好处) such as special rates on hotel rooms, drugstore purchases, and scholarships for employees' children.
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