朗阁海外考试研究中心樊秋霜
各位考生一致认为托福阅读中最后一题最难做，在这里，我们探究一下该题型（summary题型）的做法。
一、题目设置
最后一题的要求如下：
Directions: Anintroductory sentence for a brief summary of the passage is provided below.Complete the summary by selecting the THREE answer choices that express themost important ideas in the passage. Some sentences do not belong in thesummary because they express ideas that are not presented in the passage or areminor ideas in the passage. This question is worth 2 points.
二、考察内容
短时间内找出6个选项中总结文章大意的3个正确答案选项。
三、考察重点
快速总结文章大意，识别文章细节和原文中没有明确指出的选项。
四、做题方法
1.总结段落大意
2.检查6个选项，排除细节和原文中没有明确指出的选项。
短时间内快速从六个选项中判断出总结原文的选项，并排除细节和原文中没有提到的选项是重中之重。
我们以下面这道题为例，具体进行讲解。本题来自TPO 5MINERALS
AND PLANTS:
Directions: Anintroductory sentence for a brief summary of the passage is provided below.Complete the summary by selecting the THREE answer choices that express themost important ideas in the passage. Some sentences do not belong in thesummary because they express ideas that are not presented in the passage or areminor ideas in the passage. This question is worth 2 points.
Plants need to absorb certain minerals fromthe soil in adequate quantities for normal growth and development.
AnswerChoices
A. Some plants areable to accumulate extremely high levels of certain minerals and thus can beused to clean up soils contaminated with toxic levels of these minerals.
B. Though beneficialin lower levels, high levels of salts, other minerals, and heavy metals can beharmful to plants.
C. When plants do notabsorb sufficient amounts of essential minerals, characteristic abnormalitiesresult.
D. Because highconcentrations of sodium chloride and other salts limit growth in most plants,much research has been done in an effort to develop salt-tolerant agriculturalcrops.
E. Some plants cantolerate comparatively low levels of certain minerals, but such plants are oflittle use for recycling nutrients back into depleted soils.
F. Mineraldeficiencies in many plants can be cured by misting their roots with a nutrientsolution or by transferring the plants to a soilless nutrient solution.
首先，总结段落大意。大部分托福阅读文章的段落大意都是每段话首尾句结合在一起即可。如果首尾句结合在一起之后，依然无法判断，可以扫读一下段落中间部分内容（不要看for
example, for instance, such as, like,破折号，冒号之后的内容以及括号里边的内容，因为都不是中心思想）。大家可以看下面一段话：
Paragraph 1:Research has shown that certain minerals are required by plants for normalgrowth and development. The soil is the source of these minerals, which areabsorbed by the plant with the water from the soil. Even nitrogen, which is agas in its elemental state, in normally absorbed from the soil as nitrate ions.Some soils are notoriously deficient in micro nutrients and are thereforeunable to support most plant life. So-called serpentine soils, for example, aredeficient in calcium, and only plants able to tolerate low levels of thismineral can survive. In modern agriculture, mineral depletion of soils is amajor concern, since harvesting crops interrupts the recycling of nutrientsback to the soil.
通过上面的方法，我们可以判断出来，本段话主旨应该是第一句和最后一句，即：
“Research has shown
that certain minerals are required by plants for normal growth and
development.”和“Inmodern agriculture, mineral depletion of soils is a major concern, sinceharvesting crops interrupts the recycling of nutrients back to the soil.”
通过阅读这两句话，我们发现，本段话的主旨应该是：植物需要某些矿物质进行正常的生长和发展。再阅读本段话中间部分内容，发现是在讲土壤和矿物质之间的关系，印证了段落大意的总结是没有问题的。
Paragraph 2:Mineral deficiencies can often be detected by specific symptoms such aschlorosis (loss of chlorophyll resulting in yellow or white leaf issue),necrosis (isolated dead patches), anthocyanin formation (development of deepred pigmentation of leaves or stem), stunted growth, and development of woodytissue in an herbaceous plant. Soils are most commonly deficient in nitrogenand phosphorus. Nitrogen-deficient plants exhibit many of the symptoms justdescribed. Leaves develop chlorosis; stems are short and slender, andanthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces.Phosphorus-deficient plants are often stunted, with leaves turning acharacteristic dark green, often with the accumulation of anthocyanin.Typically, older leaves are affected first as the phosphorus is mobilized toyoung growing tissue. Iron deficiency is characterized by chlorosis betweenveins in young leaves.
用同样的方法判断出，本段话的主旨（首尾句）：植物缺乏某些矿物质，会产生一些症状。
Paragraph 3:Much of the research on nutrient deficiencies is based on growing plantshydroponically, that is, in soilless liquid nutrient solutions. This techniqueallows researchers to create solutions that selectively omit certain nutrientsand then observe the resulting effects on the plants. Hydroponics hasapplications beyond basic research, since it facilitates the growing ofgreenhouse vegetables during winter. Acroponics, a technique in which plantsare suspended and the roots misted with a nutrient solution, is another methodfor growing plants without soil.
本段主旨（首尾句）：我们可以用水培法来检测矿物质缺乏的症状。
Paragraph 4:While mineral deficiencies can limit the growth of plants, an overabundance ofcertain minerals can be toxic and can also limit growth. Saline soils, which havehigh concentrations of sodium chloride and other salts, limit plant growth, andresearch continues to focus on developing salt-tolerant varieties ofagricultural crops. Research has focused on the toxic effects of heavy metalssuch as lead, cadmium, mercury, and aluminum; however, even copper and zinc,which are essential elements, can become toxic in high concentrations. Althoughmost plants cannot survive in these soils, certain plants have the ability totolerate high levels of these minerals.
本段主旨（首尾句）：矿物质缺乏或过多都会限制植物生长。
Paragraph 5:Scientists have known for some time that certain plants, called hyperaccumulators, can concentrate minerals at levels a hundredfold or greater thannormal.A survey of known hyperaccumulators identified that 75 percent of them amassed nickel, cobalt, copper,zinc, manganese, lead, and cadmium are other minerals of choice. Hyperaccumulators run the entire range of the plant world. They may be herbs,shrubs, or trees. Many members of the mustard family, spurge family, legumefamily, and grass family are top hyper accumulators. Many are found in tropicaland subtropical areas of the world, where accumulation of high concentrationsof metals may afford some protection against plant-eating insects and microbialpathogens.
本段主旨（首尾句）：科学家们知道某些植物（超积累物种）可以吸收高含量的矿物质。
Paragraph 6:Only recently have investigators considered using these plants to cleanup soil and waste sites that have been contaminated by toxic levels of heavymetals – an environmentally friendly approach known as phytoremediation.This
scenario begins with the planting of hyper accumulating species in the target
area, such as an abandoned mine or an irrigation pond contaminated by runoff.Toxic minerals would first be absorbed by roots but later relocated to the stemand leaves. A harvest of the shoots would remove the toxic compounds off siteto be burned or composted to recover the metal for industrial uses. Afterseveral years of cultivation and harvest, the site would be restored at a costmuch lower than the price of excavation and reburial, the standard practice forremediation of contaminated soils. For examples, in field trials, the plantalpine pennycress removed zinc and cadmium from soils near a zinc smelter, andIndianmustard,native to Pakistan and India, has been effective in reducing levels of seleniumsalts by 50 percent in contaminated soils.
本段主旨（首尾句）：科学家们开始用这些超积累物种治理土壤污染，该方法叫植物修复。
接下来，根据上面总结的中心思想，排除错误选项：
A.
Some plants are able to accumulate extremely high levels of certain minerals
and thus can be used to clean up soils contaminated with toxic levels of these
minerals.与paragraph 5的主旨一致，选择。
B.
Though beneficial in lower levels, high levels of salts, other minerals, and
heavy metals can be harmful to plants.与paragraph
4主旨一致，选择。
C.
When plants do not absorb sufficient amounts of essential minerals,
characteristic abnormalities result.与paragraph
1主旨一致，选择。
D.Because high concentrations of sodium chloride and other salts limit growth inmost plants, much research has been done in an effort to develop salt-tolerantagricultural crops.
该选项的重心在sodium
chloride and other salts,我们用scanning的方法，定位到paragraph 4中间部分，即“Saline
soils, which have high concentrations of sodium chloride and other salts, limit
plant growth, and research continues to focus on developing salt-tolerant
varieties of agricultural crops.”该句是第四段第二句，是个并列句，并没有提到任何选项中的因果关系和意思，排除。
E.
Some plants can tolerate comparatively low levels of certain minerals, but such
plants are of little use for recycling nutrients back into depleted soils.本选项的意思是即便植物可以忍受较低含量的某种矿物质，但是这种植物对将营养循环到土壤里没有用。用scanning定位到第一段“So-called
serpentine soils, for example, are deficient in calcium, and only plants able
to tolerate low levels of this mineral can survive. In modern agriculture,
mineral depletion of soils is a major concern, since harvesting crops
interrupts the recycling of nutrients back to the soil.”这两句话和选项的意思完全不一样，并没有转折的意思，排除。
F.
Mineral deficiencies in many plants can be cured by misting their roots with a
nutrient solution or by transferring the plants to a soilless nutrient
solution.根据本选项的mineral deficiency可以定位到原文第三段“Much of the research on nutrient deficiencies is based
on growing plants hydroponically, that is, in soilless liquid nutrient
solutions. This technique allows researchers to create solutions that
selectively omit certain nutrients and then observe the resulting effects on
the plants.”这两句话是为了证明用水耕方法观测矿物质缺乏的影响，并没有说矿物质缺乏可以被cured,排除。
因此，正确答案为：A, B, C。
相信通过上面的讲解，大家应该明白了如何做最后一题，希望大家能在短时间内快速准确做完最后一题。
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