Colonizationis one way in which plants can change theecologyof a site. Colonizationis aprocesswith two components:invasionandsurvival. Therateat which a site is colonized by plants depends on both therateat whichindividualorganisms (seeds, spores,immatureormatureindividuals) arrive at the site and their success at becoming established and surviving. Success incolonizationdepends to a greatextenton there being a siteavailableforcolonization– a safe site wheredisturbanceby fire or by cutting down of trees has either removedcompetingspeciesor reduced levels of competition and othernegativeinteractions to alevelat which the invadingspeciescan become established. For agivenrateofinvasion,colonizationof amoist,fertilesite is likely to be much more rapid than that of a dry, infertile site because of poorsurvivalon thelatter. Afertile, plowedfieldis rapidly invaded by a largevarietyof weeds, whereas a neighboringconstructionsite from which the soil has been compacted or removed toexposeacoarse, infertile parentmaterialmayremainvirtuallyfree ofvegetationfor many months orevenyears despite receiving the same input of seeds as the plowedfield.

Both therateofinvasionand therateofextinctionvarygreatly among different plantspecies. Pioneerspecies- those thatoccuronly in the earliest stages ofcolonization-tendto have high rates ofinvasionbecause they produce very large numbers ofreproductivepropagules (seeds, spores, and so on) and because they have anefficientmeans ofdispersal(normally, wind).

If colonizers produce short-livedreproductivepropagules, they must produce very large numbers unless they have anefficientmeans ofdispersaltosuitablenew habitats. Many plantsdependon wind fordispersaland produceabundantquantities of small,relativelyshort-lived seeds tocompensatefor the fact that wind is not always areliablemeans If reaching theappropriatetype ofhabitat. Alternativestrategies have evolved in some plants, such as those that produce fewer but larger seeds that are dispersed tosuitablesites by birds or small mammals or those that produce long-lived seeds. Many forest plantsseemtoexhibitthelatteradaptation, andviableseeds ofpioneerspeciescan be found in large numbers on some forest floors. For example, as many as 1,125viableseeds persquaremeter were found in a 100-year-old Douglas fir/western hemlock forest in coastal British Columbia. Nearly all the seeds that had germinated from this seed bank were frompioneerspecies. The rapidcolonizationof such sites afterdisturbanceis undoubtedly in part areflectionof the large seedbandon the forest floor.

Anadaptationthat is well developed in colonizingspeciesis a highdegreeofvariationin germination (the beginning of a seed’s growth). Seeds of agivenspeciesexhibita wide range of germination dates, increasing the probability that atleastsome of the seeds willgerminateduring a period offavorableenvironmentalconditions. This is particularly important forspeciesthatcolonizean environment where there is no existingvegetationtoameliorateclimaticextremes and in which there may be greatclimaticdiversity.

Speciessuccessionin plant communities, i.e., thetemporalsequenceofappearanceand disappearance ofspeciesis dependent on events occurring at different stages in the lifehistoryof aspecies. Variationin rates ofinvasionand growth plays an important role in determining patterns ofsuccession, especially secondarysuccession. Thespeciesthat are first tocolonizea site are those that produceabundantseed that is distributed successfully to new sites. Suchspeciesgenerally grow rapidly and quicklydominatenew sites, excluding otherspecieswithlowerinvasionand growth rates. The firstcommunitythat occupies a disturbed areathereforemay be composed of specie with the highestrateofinvasion, whereas thecommunityof thesubsequentstagemayconsistof plants withsimilarsurvivalrates butlowerinvasionrates.

Questions:
question_stem: According to paragraph 1, how does disturbance of a site influence its colonization by a plant species?
choices: tag: A
text: Disturbance reduces or eliminates competition by other species.

tag: B
text: Disturbance increases negative interactions with other organisms on the site.

tag: C
text: Disturbance prevents a plant species from colonizing a new site.

tag: D
text: Disturbance reduces the fertility of a site.
answer_key: A
explanation: 用题干关键词"disturbance"定位到第1段第4句话：Success in colonization depends to a great extent on there being a site available for colonization – a safe site where disturbance by fire or by cutting down of trees has either removed competing species or reduced levels of competition and other negative interactions to a level at which the invading species can become established. 这里说了，通过火灾和砍伐的干涉要么消除竞争对手要么降低竞争的强度。这和 A 选项中的 eliminates competition 呼应。B 选项的 increase negative interations 和原文 reduced other negative interations 相反，所以错；C 说反；D 在原文无提及。

question_stem: The word “virtually” in the passage is closest in meaning to
choices: tag: A
text: almost totally

tag: B
text: unusually

tag: C
text: consistently

tag: D
text: unnaturally
answer_key: A
explanation: virtually: 实际上; 几乎, 对应 A 选项的 almost totally（几乎完全）对应原文：A fertile, plowed field is rapidly invaded by a large variety of weeds, whereas a neighboring construction site from which the soil has been compacted or removed to expose a coarse, infertile parent material may remain virtually free of vegetation for many months or even years despite receiving the same input of seeds as the plowed field.这句话的主要逻辑是转折，前后内容形成对立，即：is invaded by a large variety of weeds 和 remain virtually free of vegetation 对立。那么，就可以利用这个关系来进行推测。B 选项的 unusually（异乎寻常地），C 选项的 consistently（一贯地），D 选项的 unnaturally（不自然地）代入后明显不合适，只有 A 选项最为合适，内容能够形成很好的转折。

question_stem: Why does the author mention a plowed field and a construction site in the passage?
choices: tag: A
text: To argue that sites that have been affected by human activity tend to be colonized slowly

tag: B
text: To illustrate the kind of sites that may be invaded by weeds

tag: C
text: To contrast sites in terms of their suitability for colonization

tag: D
text: To explain that exposing or compacting the soil results in successful colonization
answer_key: C
explanation: 用 plowed field and a construction site 先定位细节出处整段最后一句话，那么这个细节所支撑的目的句要么在它前1.2句，要么就是整段的主旨句了。很明显，其所突出的目的句就是前一句话，结合这两句话来进行选择：For a given rate of invasion, colonization of a moist, fertile site is likely to be much more rapid than that of a dry, infertile site because of poor survival on the latter.这句话的内容只要是说，入侵肥沃的土地比那些干涸的、不肥沃的土地要来的快很多。这就和 C 选项呼应。

question_stem: The word “despite” in the passage is closest in meaning to
choices: tag: A
text: without

tag: B
text: almost never

tag: C
text: even though

tag: D
text: perhaps
answer_key: C
explanation: despite 尽管,；对应 even though 尽管/即使。A fertile, plowed field is rapidly invaded by a large variety of weeds, whereas a neighboring construction site from which the soil has been compacted or removed to expose a coarse, infertile parent material may remain virtually free of vegetation for many months or even years despite receiving the same input of seeds as the plowed field.这句话的主要逻辑是 whereas 引导的转折，转折前后内容对立，那么 despite 必定不能是这种对立关系矛盾，所以就可以尝试将4个选项代入，看看哪一个是转折关系成立，且语义连贯。只有 C 选项最合适，意思是“尽管收到了同样多的种子，干涸不肥沃的土地上可能还是没有植物”和转折前的肥沃土地的状态形成了鲜明的对立关系。

question_stem: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
choices: tag: A
text: The seeds of pioneer species are usually carried by the wind to fertile sites, where they reproduce very efficiently.

tag: B
text: Pioneer species are successful invaders because they produce lots of seeds that are dispersed effectively.

tag: C
text: Pioneer species produce their largest numbers of propagules during the earliest stages of their colonization.

tag: D
text: Pioneer species reproduce very quickly and efficiently because they produce very large number of seeds.
answer_key: B
explanation: 原句从逻辑结构上来看，最主要的逻辑是因果逻辑，而原因陈述中则有一个并列逻辑，将这两个逻辑的核心内容和选项进行匹配。 原句强调了先锋物种入侵速度快的2个原因, 一是能够产生大量可繁殖的种子, 二是拥有有效的传播途径. 原句和 fertile sites 没有关系,A 错; C 没有提到种子的繁殖力; D 没有提到传播途径. 只有 B 满足原句的条件。

question_stem: What can be inferred from paragraph 3 about the reason that large seeds are dispersed by birds or small animals rather than by wind?
choices: tag: A
text: Large seeds are easier for birds and animals to see than are the small seeds dispersed by the wind.

tag: B
text: Large seeds are too heavy for the wind to disperse.

tag: C
text: Large seeds cannot be eaten by birds and animals.

tag: D
text: Large seeds are short-lived and thus require a more efficient means of dispersal than small seeds do.
answer_key: B
explanation: 用 large seeds 可定位到原文第3句，但是，第三句不足以用来推测，还需结合讨论 seed 传播方式的第二句话，这两句话将小种子和大种子传播方式做了介绍：Many plants depend on wind for dispersal and produce abundant quantities of small, relatively short-lived seeds to compensate for the fact that wind is not always a reliable means of reaching the appropriate type of habitat. Alternative strategies have evolved in some plants, such as those that produce fewer but larger seeds that are dispersed to suitable sites by birds or small mammals or those that produce long-lived seeds.这两句话的主要内容是：小种子通常靠风传播, 大种子由鸟和动物实现传播。而在说道风这个传播媒介是，提到它的特性是 not reliable 的。后面就接着说大种子依赖其他的途径传播，言下之意就是大种子太重了，风很难传播。那么就和 B 选项的内容呼应。

question_stem: The phrase “the latter adaptation” in the passage refers to
choices: tag: A
text: producing fewer seeds

tag: B
text: producing larger seeds

tag: C
text: dispersal by birds and small mammals

tag: D
text: producing long-lived seeds
answer_key: D
explanation: 原文出处：Alternative strategies have evolved in some plants, such as those that produce fewer but larger seeds that are dispersed to suitable sites by birds or small mammals or those that produce long-lived seeds. Many forest plants seem to exhibit the latter adaptation and viable seeds of pioneer species can be found in large numbers on some forest floors.

the latter adaptation,指代的是前面提到的两种适应方法的后一种，所以我们需要往前找答案。前一句话提到2种适应性：第一种是生产少一点，但是个头更大的种子，可以被鸟类或其他小的哺乳动物传播到合适的地方；第二种就是生产 long-lived seeds, 所以后一种适应性是指长命种子。所以 D 选项正确。

question_stem: The word “viable” in the passage is closest in meaning to
choices: tag: A
text: able to survive

tag: B
text: individual

tag: C
text: large

tag: D
text: remaining
answer_key: A
explanation: viable：能养活的； 能自行生产发育的, 对应 A 选项的 able to survive 能存活的。对应原文：For example, as many as 1,125 viable seeds per square meter were found in a 100-year-old Douglas fir/western hemlock forest in coastal British Columbia. Viable 这个单词同学们普遍了解的那层意思是“可行的”，可以通过这个意思来进行推测，就算有其他意思也不会相差太多。和明显 B 选项 individual（个人的），C 选项的 large（大的），D 选项的 remaining（剩下的）明显和“可行的”这层意思不沾边。只有 A 选项最为合适。且原文的大致是在说在这个树林中发现的可以存活的种子数量之多。

question_stem: The example of the 100-year-old Douglas fir/western hemlock forest in paragraph to illustrates which of the following ideas?
choices: tag: A
text: It is uncommon for older seed to germinate.

tag: B
text: Pioneer species tend to prefer forest floors for colonization purposes.

tag: C
text: Long-lived seeds of pioneer species can successfully germinate over long periods of time.

tag: D
text: Coastal British Columbia is particularly suited for pioneer species to develop.
answer_key: C
explanation: 该例子的前一句话为观点句, 例子是为了说明观点, 需要重点分析的观点句为：Many forest plants seem to exhibit the latter adaptation, and viable seeds of pioneer species can be found in large numbers on some forest floors. 其内容主要是说，长命种子在森林地面上很繁荣。和 C 选项呼应。

question_stem: According to paragraph 4, how do plants manage to germinate in areas with great climatic diversity and climatic extremes?
choices: tag: A
text: By producing seeds only during favorable climatic conditions

tag: B
text: By generating large numbers of seeds

tag: C
text: By colonizing only those areas where other plants have survived

tag: D
text: By producing seeds that have a wide range of germination dates
answer_key: D
explanation: 用 climatic diversity 定位到这一段最后一句话，但这句话只做了总结，没有具体描述这些植物是如何 germinate 的，所以需要阅读前文的内容，而答案则出现在该段的第2句话：Seeds of a given species exhibit a wide range of germination dates, increasing the probability that at least some of the seeds will germinate during a period of favorable environmental conditions.这里主要强调了这些种子有着很大范围的发芽期，和 D 选项呼应。A 选项的 only 太过绝对，原文没有这么说；B 选项并不是可以在极端气候存活的原因，答非所问；C 选项在原文无提及。

question_stem: The word “abundant” in the passage is closest in meaning to
choices: tag: A
text: new

tag: B
text: improved

tag: C
text: suitable

tag: D
text: plentiful
answer_key: D
explanation: abundant: 丰富的, 对应 D 选项的 plentiful（丰富的，许多的）。
对应原文：The species that are first to colonize a site are those that produce abundant seed that is distributed successfully to new sites.通过对应原文，大致可以理解到：第一批移入的物种是那些可以生产 abundant 种子的那些，这些种子会成功地分布在新的地方。再联系上下文，abundant 肯定要和种子成功移植到别的地点的特性有关，所以，这些选项中只有 D 最为合适。

question_stem: According to paragraph 5, which of the following determines the sequence in which plant species will colonize a site?
choices: tag: A
text: The extent of growth of a species on a prior site before it begins to colonize a secondary site

tag: B
text: The differences in invasion and growth rates across species

tag: C
text: The degree of fertility of a site

tag: D
text: The kind of disturbance that the site has undergone
answer_key: B
explanation: 用 sequence 定位到该段第一句话，第一句话太过笼统，需要继续往下看。而该段第二句话点出了决定 sequence 的要素：
Variation in rates of invasion and growth plays an important role in determining patterns of succession, especially secondary succession. The species that are first to colonize a site are those that produce abundant seed that is distributed successfully to new sites.这里明确说的熬了是 Variation in rates of invasion and growth 起到了重要的作用，和 B 选项呼应。ACD 选项都没有提及。