[外语类试卷]大学英语四级模拟试卷157(无答案).doc
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1、大学英语四级模拟试卷 157(无答案)一、Part I Writing (30 minutes)1 For this part, you are allowed 30 minutes to write a composition on the topic: what Jobs Do College Graduates What to Take? You should write at least 120 words following the-outline given below in Chinese:Occupation Male FemaleTeaching 5% 45%Managers
2、 40% 15%Businessmen 30% 25%Lawyers 15% 10%1目前大学毕业生的择业情况2男、女学生就业选择的区别3我的观点二、Part II Reading Comprehension (Skimming and Scanning) (15 minutes)Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-7, mark:Y (
3、for YES) if the statement agrees with the information given in the passage;N (for NO) if the statement contradicts the information given in the passage;NG (for NOT GIVEN) if the information is not given in the passage.1 To Save Trees, Fighting One Alien Insect with OthersRusty Rhea sighs wistfully a
4、s he talks about the beauty and peace of standing amid a grove (小树林) of deep green hemlocks in Appalachia, some of them up to 160 feet (50 meters) tall and more than 500 years old.“This is a very special tree,“ said Rhea, an entomologist for the U.S. Forest Services Forest Health Protection program
5、in Asheville, North Carolina. “I was brought up here, and I dont want to see another species go by the wayside.“The evergreen trees, a hallmark of southern Appalachias national parks, are under attack by an invasive insect barely visible to the eye but potent enough to fell the giants of the eastern
6、 United States old-growth forests.Already the tiny bug from Japan, known as the hemlock woolly adelgid (HWA), has killed upward of 95 percent of the hemlocks in Virginias Shenandoah National Park. Now they are making their way through the half-million-plus-acre (200,000-plus-hectare) Great Smoky Mou
7、ntains National Park in North Carolina and Tennessee.The hemlocks shade streams, keeping water temperatures just right for brook trout(鲑鱼) and other fish. They also house birds such as the black-throated green warbler, solitary vireo, and northern goshawk, all three of which mainly shelter in stands
8、 of hemlock trees.Because of the insects broad impact on the entire ecosystem of southern Appalachia, HWA stands to cause wider damage than the American chestnut blight(枯萎病) of the early 1900s. That fungus from Europe killed off the once dominant chestnut trees from the northeast United States to th
9、e southern Appalachian Mountains.In addition, a species related to HWA, the balsam woolly adelgid, has already killed about 90 percent of the mature Fraser fir trees in the Smokies.Acting QuicklyHWA arrived in the U.S. Pacific Northwest via nursery plants from Japan in 1924. By 1951 the tiny invader
10、 had been found in Virginia. Since then the insect has spread to more than 15 U.S. states.The key to killing the HWA is to catch it early and act quickly. Its already well established in the Great Smoky Mountains, where Rhea and others are trying to stem the spread of the bugs.HWA multiply quickly:
11、All of the insects are females that reproduce asexually (无性地), laying several hundred eggs a year. When they get to the nymph, or crawler, stage, they are dormant from about June until October, after which they emerge and establish themselves on trees.Winds and birds and other animals spread the cra
12、wlers through the forest.HWA crawlers feed on the new growth of hemlocks by piercing the twigs that hold the branches, sucking the sap, and injecting toxic saliva. The needles turn from a deep green to a grayish green and eventually die, depriving the tree of nutrition from photosynthesis.An infecte
13、d tree usually dies within five years of initial attack. Infection is signaled by either a white, cottonlike material that appears along a trees twigs or by the “baldness“ of a trees upper branches.Plans of AttackIn the Pacific Northwest the hemlocks seem to be tolerant of the creatures feeding, and
14、 in the cold northeast, winters seem to keep them at bay. But in the warm southeast, with weather approximating that of the insects native Asian homes, they thrive.Chemical sprays-such as insecticidal soaps and horticultural oils as well as trunk or soil injections-have helped to kill some of the HW
15、A infestations.years at most. These methods cant be used conveniently or safely in remote areas or near the streams where hemlocks grow thickly.Long term, the best way to control the pests appears to be releasing other insects that feed exclusively on HWA. Scientists have studied HWA in Japan and Ch
16、ina and identified three such species. One of them, the Sasajiscymnus tsugae (St) beetle, was released in areas of Great Smoky Mountains National Park in 2002.Studying what controls a species in its native habitat-including climate, predators, and host resistance-provided clues about which insects t
17、o use against HWA, said Kristine Johnson. Based in Gatlinburg, Tennessee, Johnson is a supervisory forester for Great Smoky Mountains National Park.“Biological control is the only long-term hope to save the trees in the backcountry(穷乡僻壤),“ she said. “We have 800 square miles (2,100 square kilometers
18、) of contiguous wilderness. We value the native forest, and its entirely worth defending.“Risky BusinessReleasing one species of non-native bug to kill another could be risky business, potentially creating another type of infestation. But scientists first quarantined and studied the HWA-killer insec
19、ts.They believe the St beetles are the best answer to the HWA problem and that they wont cause side damage. This tiny black female beetle, the size of a poppy seed, is already spreading in the Great Smoky Mountains.But the beetle and other HWA-killer insects are seasonal, so it will take several dif
20、ferent ones operating year-round to keep HWA in check, Rhea said. He doesnt believe HWA will be completely eradicated (根除) but will instead be kept in balance by the predator insects. “Were trying to insert a balance in a system thats out of balance,“ he said.Each St beetle can lay 200 to 300 eggs,
21、said Ernest Bernard, professor of entomology and plant pathology at the University of Tennessee in Knoxville.Bernards laboratory is one of several that are breeding the beetles.“Each beetle eats hundreds of baby adelgids a year,“ he said. And about 120,000 of the beetles have been released in the pa
22、st couple years in the Smokies, but it is still too early to measure their impact.One good sign, Bernard said, is that some beetle larvae (幼虫) have been found in areas where they were not released, indicating that the HWA killers may be reproducing and spreading.2 The passage gives a general descrip
23、tion of an invasive insect, HWA.(A)Y(B) N(C) NG3 Hemlock is a hallmark of southern Appalachias national parks.(A)Y(B) N(C) NG4 The invasive insect, known as the hemlock woolly adelgid (HWA), is from Japan.(A)Y(B) N(C) NG5 The key to killing the HWA is to catch it early and act quickly.(A)Y(B) N(C) N
24、G6 An infected tree usually dies immediately.(A)Y(B) N(C) NG7 The Hemlock in the U.S. will be saved from HWA soon.(A)Y(B) N(C) NG8 The long term, best way to control the pests HWA is spraying.(A)Y(B) N(C) NG9 Since 1951 the HWA has spread to more than _.10 Releasing one species of non-native bug to
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