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Questions 31-40 Growing tightly packed together and collectively weaving a dense1 canopy2 of branches,a stand of red alder3 trees can totally dominate a site to the exclusion4 of almost everything else.Certain species such as salmonberry and sword ferns have Line adapted to the limited sunlight dappling through the canopy,but few evergreen5 trees (S)will survive there;still fewer can compete with the early prodigious6 growth of alders7.A Douglas fir tree reaches its maximum rate of growth ten years later than an alder,and if the two of them begin life at the same time,the alder quickly outgrows8 and dominates the Douglas fir.After an alder canopy has closed,the Douglas fir suffers a marked decrease in growth,often dying within seven years.Even more shade-tolerant species of trees such as hemlock9 may remain badly suppressed beneath aggressive young alders. Companies engaged in intensive timber cropping naturally take a dim view of alders suppressing more valuable evergreen trees.But times are changing;a new generation of foresters seems better prepared to Include in their management plans consideration of the vital ecological10 role alders,play. Among the alder's valuable ecological contributions is its capacity to fix nitrogen in nitrogen-deficient soils.Alder roots contain clusters of nitrogen-fixing nodules like those found on legumes such as beans.in addition,newly developing soils exposed by recent glacier11 retreat and planted with alders show that these trees are applying the equivalent of ten bags of high-nitrogen fertilizer to each hectare per year.Other chemical changes to soil in which they are growing Include a lowering of the base content and rise In soil acidity,as well as a substantial addition of carbon and calcium12.to the soil, Another important role many alders play in the wild,particularly in mountainous areas,is to check the rush of water during spring melt.In Japan and elsewhere,the trees are planted to stabilize13 soil on steep mountain slopes.Similarly,alders have been planted to stabilize and rehabilitate14 waste material left over from old mines,flood deposits,and landslide15 areas in both Europe and Asia. 31.What does the passage mainly discuss? (A)Differences between alder trees and Douglas fir trees (B)Alder trees as a source of timber (C)Management plans for using alder trees to improve soil (D)The relation of alder trees to their forest environments 32.The word "dense"in line I is closest in meaning to (A)dark (B)tall (C)thick (D)broad 33.Alder trees can suppress the growth of nearby trees by depriving them of (A)nitrogen (B)sunlight (D)water 34.Thc passage suggests that Douglas fir trees are (A)a type of alder (B)a type of evergreen (C)similar to sword ferns (D)fast-growing trees 35.It can be inferred from paragraph I that hemlock trees (A)are similar in size to alder trees. (B)interfere with the growth of Douglas fir trees (C)reduce the number of alder trees In the forest (D)need less sunlight than do Douglas fir trees 36.It can be inferred from paragraph 2that previous generations of foresters (A)did not study the effects of alders on forests (B)did not want alders In forests (C)harvested alders for lumber17 (D)used alders to control the growth of evergreens18 37.The word "they"in line 21refers to (A)newly developing soils (B)alders (C)bags (D)chemical changes 38.According to the passage that alders are used in mountainous areas to (A)nitrogen (B)calcium (C)carbon (D)oxygen 39.It can be Inferred from the passage that alders are used in mountainous areas to (A)prevent water from carrying away soil (B)hold the snow (C)protect mines (D)provide material for housing 40.What is the author's main purpose in the passage? (A)To argue that alder trees are useful in forest management (B)To explain the life cycle of alder trees (C)To criticize the way alders take over and eliminate forests (D)To illustrate19 how alder trees control soil erosion Questions 41-50 In taking ups new life across the Atlantic,the early European settlers of the United States did not abandon the diversions with which their ancestors had traditionally relieved the tedium20 of life.Neither the harshness of existence on the new continent nor Line the scattered21 population nor the disapproval22 of the clergy23 discouraged the majority from the pursuit of pleasure. City and country dwellers24.of course.conducted this pursuit in different ways.Farm dwellers in their isolation25 not only found it harder to locate companions in play but also thanks to the unending demands and pressures of their work,felt it necessary to combine fun with purpose.No other set of colonists26 too so seriously one expression of the period."Leisure Is time for doing something useful."in the countryside farmers therefore relieved the burden of the daily routine with such relaxation27 as hunting.fishing,and trapping.When a neighbor needed help,families rallied from miles around to assist In building a house or barn,husking corn,shearing sheep.or chopping wood.Food,drink,and celebration after the group work provided relaxation and soothed28 weary muscles. The most eagerly anticipated social events were the rural fairs,Hundreds of men,women,and children attended from far and near.The men bought or traded farm animals and acquired needed merchandise while the women displayed food prepared in their kitchens,and everyone,Including the youngsters,watched or participated in a variety of competitive sports,with prizes awarded to the winners.These events typically included horse races,wrestling matches,and foot races,as well as some nonathletic events such as whistling competitions.No other occasions did so much to relieve the isolation of farm existence. With the open countryside everywhere at hand,city dwellers naturally shared in some of the rural diversions.Favored recreations included fishing,hunting1skating,and swimming.But city dwellers also developed other pleasures.which only compact communities made possible. 41.What is the passage mainly about? (A)Methods of farming used by early settlers of the United States (B)Hardships faced by the early settlers of the United States (C)Methods of buying,selling,and trading used by early settlers of the United States (D)Ways in which early settlers of the United States relaxed 42.What can be inferred about the diversions of the early settlers of the United States? (A)They followed a pattern begun in Europe. (B)They were enjoyed more frequently than in Europe. (C)The clergy organized them. (D)Only the wealthy participated in them. 43.Which of 'he following can be said about the country dwellers'attitude toward "the pursuit of pleasure"? (A)They felt that it should help keep their minds on their work. (B)They felt that it was not necessary. (C)They felt that it should be.productive. (D)They felt that it should not involve eating and drinking. 44.The phrase "thanks to"in line 8is closest in meaning to (A)grateful for (B)help with (C)because of (D)machines for 45.The word "their"in line B refers to (A)ways (B)farm dwellers (C)demands (D)pressures 46.What is meant by the phrase "double-purpose"in line 11? (A)Very frequent (B)Useful and enjoyable (C)Extremely necessary (D)Positive and negative 47.The phrase "eagerly anticipated"in line 16is closest in meaning to (A)well organized (B)old-fashioned (C)strongly opposed (D)looked forward to 48.Which of the following can be said about the rural diversions mentioned in the last paragraph in which city dwellers also participated? (A)They were useful to the rural community. (B)They involved the purchase items useful in the home. (C)They were activities that could be done equally easily in the towns (D)They were all outdoor activities. 49.What will the author probably discuss in the paragraph following this passage? (A)The rural diversions enjoyed by both urban and rural people (B)Leisure activities of city dwellers (C)Building methods of the early settlers in rural areas (D)Changes in the lifestyles of settlers'as they moved to the cities 50.Where in the passage does the author mention factors that might prevent people from enjoying themselves? (A)Lines 3-5 (B)Lines 12-14 (C)Lines 17-20 (D)Lines 25-27 点击收听单词发音
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