If a diver surfaces too quickly, he may suffer the bends. Nitrogen (氮) dissolved (溶解) in his blood is suddenly liberated by the reduction of pressure. The consequence, if the bubbles (气泡) accumulate in a joint, is sharp pain and a bent body — thus the name. If the bubbles form in his lungs or brain, the consequence can be death.
Other air-breathing animals also suffer this decompression (减压) sickness if they surface too fast: whales, for example. And so, long ago, did ichthyosaurs (鱼龙). That these ancient sea-animals got the bends can be seen from their bones. If bubbles of nitrogen form inside the bone they can cut off its blood supply. This kills the cells in the bone, and consequently weakens it, sometimes to the point of collapse. Fossil(化石)bones that have caved in on themselves are thus a sign that the animal once had the bends.
Bruce Rothschild of the University of Kansas knew all this when he began a suty of ichthyosaurs bones to find out how widespread the problem was in the past. What he particularly wanted to investigate was how ichthyosaurs adapted to the problem of decompession over the 150 milllion years. To this end, he and his colleagues traveled the world’s natural-history museums, looking at hundreds of ichthyosaurs from the Trassic period and from the later Jurassic and Cretaceous periods.
When he started, he assumed that signs of the bends would be rarer in younger fossils, reflecting their gradual evolution of measures to deal with decompression. Instead, he was astonished to discover the opposite. More than 15% of Jurassic and Cretaceous ichthyosaurs had suffered the bends before the died, but not a single Trassic specimen showed evidence of that sort of injury.
If ichthyosaurs did evolve an anti-decompression means, they clearly did so quickly — and, most strangly, they lost it afterwards. But that is not what Dr Rothchild thinks happened. He suspects it was evolution in other animals that caused the change.
Whales that suffer the bends often do so because they have sufaced to escape a predator (捕食动物) such as a large shark. One of the features of the Jurassia oceans was an abundance of large sharks and crocodiles, both of which were fond of ichthyosaurs lunches. Trassic oceans, by contrast, were mercifully shark-and crocodile-free. In the Trassic, then, ichthyosaurs were top of the food chain. In the Jurrasic and Cretaceous, they were prey (猎物) as well as predator —and often had to make a speedy exit as a result.
1.Which of the following is a typical symptom of the bends?
A. A twisted body.
B. A gradual decrease in blood supply.
C. A sudden release of nitrogen in blood.
D. A drop in blood presure.
2.The purpose of Rothchild’s study is to see .
A. how often ichthyosaurs caught the bends
B. how ichthyosaurs adapted to decompression
C. why ichthyosaurs bent their bodies
D. when ichthyosaurs broke their bones
3.Rothchild’s finding stated in Paragrapg 4 .
A. confirmed his assumption B. speeded up his research process
C. disagreed with his assumption D. changed his research objectives
4.Rothchild might have concluded that ichthyosaurs .
A. failed to evole an anti-decompression means
B. grdually developed measures against the bends
C. died out because of large sharks and crocodiles
D. evoled an anti-decompression means but soon lost it
Salvation Army Angel Program
Angel Tree collects gifts for children and families in need. Participate by selecting an angel from any Angel Tree at all Cyprus Credit Union location or any Utah Macy's Department store. Shop for your angel, then return your new, unwrapped gift to the same Angel Tree. Gifts must be returned before December 14. For more information, call (801) 988-5678 in the Salt Lake area,(801) 374-2588 in the Provo area.
Utah Association for People with Intellectual Disabilities Holiday Gift Box Program
The program serves primarily low-income adults with intellectual disabilities who don't qualify for other programs because of age limits, said Joyce Whalen, the association's board president. To donate, visit the association at 1326 S.2100 East from 9am to about 5:30 pm to choose an ornament (װ����) that provides information about an individual who will benefit from the program. Shop for new items and return them by December 14. Donations of generic items, such as towels, socks and hygiene products also accepted, as are monetary donations. For more information, call 801-440-1674.
Utah Foster Care Foundation's Giving Tree Program
The program seeks new gifts and cash donations to fulfill the holiday wishes of more than 1,000 children in state-licensed foster homes." Many of the children in care have been removed from their biological homes because of neglect or abuse," said Nikki Mackay, the foundation's director. " Christmas can be a difficult time for them." To learn how to support the program, call 877-505-5437.
Utah State Hospital Forgotten Patient Program
The program provides Christmas gifts for hundreds of patients with mental illness. In the history of the program--which may go back as far as 60 years, organizer Shawna Peterson said, "we've never had a forgotten patient." And she doesn't want this year to change that. To support the program, contact Peterson at 801-344-6088.
1.After you buy an angel, you should ________.
A. post it to where you bought
B. open its package to examine it
C. send it to families in need for yourself
D. bring it back in its original form
2. If you want to help adults with intellectual disabilities, you should call_____.
A. 801-440-1674 B. 801-988-5678
C. 877-505-5437 D. 801-344-6088
3.The underlined phrases "biological homes" in the third program refers to ______.
A. homes where they are just brought up
B. homes where their natural parents live
C. homes where they learn biology
D. homes where are related to bacteria
4.From the last program, we can infer that ______.
A. the patients often forgot to come to the hospital
B. the patients are often forgotten to be looked after
C. the patients are being taken good care of
D. the patients had a poor memory in the hospital
Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour. The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.
Scientists have changed the colour of a dark-striped zebra fish to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra fish skin colour is determined by pigment cells, which contain melanosomes (黑色素体). The number, size and darkness of melanosomes per pigment cell determines skin colour.
It appears that, like the golden zebra fish, light-skinned Europeans also have a mutation (突变)in the gene for melanosome production. This results in less pigmented skin. However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra fish genes.
Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun, which can cause skin cancer. But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng. Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colours, said Cheng.
The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment done on Michael Jackson.
1.According to the passage, scientists have found .
A. people living in northern latitudes need more sunlight
B. the reason why people change their skin colour
C. the reason why people get skin cancer
D. the gene that determines skin colour
2.We can infer from the passage that .
A. people like to change their skin colour
B. a mutation in the gene for melanosome production is different in human and zebra fish gene
C. people will be able to change their skin colour without chemical treatment in the future
D. skin cancer can be cured now
3.Which of the following is NOT mentioned according to the passage?
A. The version of the pigment gene of Asians and that of Africans are the same.
B. Scientists have succeeded in turning the colour of a dark-striped zebra fish into uniform gold.
C. Dark skin can protect bodies from utral-violet rays of the sun.
D. People like pop king Michael Jackson.
4.The passage is probably taken from __________.
A. a novel B. a science report
C. a story book D. a science fiction
When I was a child, my parents taught me the difference between good and bad behavior by showing me specific examples. My mother told me that you don’t 36 other kids because you would not like 37 if they hit you. That makes 38 . But, if my mother told me to be “nice” to someone, it was too vague for me to 39 . But if she said that being nice 40 delivering daffodils to a next door neighbor, that I could understand.
I believe that doing practical things can 41 the world a better place. When I was in my twenties I thought a lot about the meaning of life. At the time, I was getting started in my 42 of designing more humane facilities for animals at big farms and slaughterhouses(屠宰场). Many people would think that to even work at a slauterhouse would be inhumane, but they 43 that every human and animal 44 dies. In my mind, I had a(n) 45 of a way to make tht dying as 46 as possible.
Back in the 1970s, I went to fifty different feedlots and big farms in Arizona and Texas and 47 them work cattle. I cataloged the parts of each facility that 48 effectively. I took the best loading ramps, and other components and 49 them into an ideal new system. I get great 50 when a farmer tells me that my corral (畜栏) 51 helps cattle move through it quietly and 52 . When cattle stay calm, it means they are not scared. And that makes me feel I’ve 53 something important.
Some people might think if I could snap my 54 I’d choose to be “normal”. But, I wouldn’t want to give up my 55 to see in beautiful, precise pictures. I believe in them.
1.A. knock B. hit C. beat D. strike
2.A. this B. which C. it D. that
3.A. sense B. difference C. sail D. way
4.A. recognize B. realize C. know D. understand
5.A. meant B. minded C. missed D. admitted
6.A. give B. turn C. make D. take
7.A. job B. career C. trade D. industry
8.A. regret B. remember C. forgive D. forget
9.A. constantly B. eventually C. immediately D. directly
10.A. description B. scene C. picture D. image
11.A. peaceful B. calm C. quiet D.silent
12.A. required B. asked C. promised D. helped
13.A. solved B. worked C. acted D. conducted
14.A. collected B. gathered C. assembled D. met
15.A. satisfaction B. expectation C. explanation D. presentation
16.A. aim B. intention C. plan D. design
17.A. hardly B. difficultly C. easily D. happily
18.A. reached B. accomplished C. adapted D. polished
19.A. fingers B. hands C. arms D. feet
20.A. skill B. possibility C. talent D. ability
It was only a very short time _______ the young lady found her cellphone stolen as she got on the crowed bus.
A. before B. when C. since D. after
When television was first introduced, the extent _______ it would affect society could not have been foreseen.
A. of which B. of what C. to which D. in which
