托福阅读真题2020

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托福阅读真题1

PASSAGE 10

One area of paleoanthropological study involves the eating and dietary habits of hominids, erect bipedal primates — including early humans. It is clear that at some stage of history, humans began to carry their food to central places, called home bases, where it was shared and consumed with the young and other adults. The use of home bases is a fundamental component of human social behavior; the common meal served at a common hearth is a powerful symbol, a mark of social unity. Home base behavior does not occur among nonhuman primates and is rare among mammals. It is unclear when humans began to use home bases, what kind of communications and social relations were involved, and what the ecological and food-choice contexts of the shift were. Work on early tools, surveys of paleoanthropological sites, development and testing of broad ecological theories, and advances in comparative primatology are contributing to knowledge about this central chapter in human prehistory.

One innovative approach to these issues involves studying damage and wear on stone tools. Researchers make tools that replicate excavated specimens as closely as possible and then try to use them as the originals might have been used, in woodcutting, hunting, or cultivation. Depending on how the tool is used, characteristic chippage patterns and microscopically distinguishable polishes develop near the edges. The first application of this method of analysis to stone tools that are 1.5 million to 2 million years old indicates that, from the start, an important function of early stone tools was to extract highly nutritious food — meat and marrow — from large animal carcasses. Fossil bones with cut marks caused by stone tools have been discovered lying in the same 2-million-year-old layers that yielded the oldest such tools and the oldest hominid specimens (including humans) with larger than ape-sized brains. This discovery increases scientists' certainty about when human ancestors began to eat more meat than present-day nonhuman primates. But several questions remain unanswered: how frequently meat eating occurred; what the social implications of meat eating were; and whether the increased use of meat coincides with the beginnings of the use of home bases.

1. The passage mainly discusses which of the following aspects of hominid behavior?

(A) Changes in eating and dietary practices

(B) The creation of stone hunting tools

(D) Methods of extracting nutritious food from carcasses

2. According to the passage , bringing a meal to a location to be shared by many individuals is

(A) an activity typical of nonhuman primates

(B) a common practice among animals that eat meat

(D) a behavior that encourages better dietary habits

3. The word consumed in line 4 is closest in meaning to

(A) prepared

(B) stored

(D) eaten

4. According to paragraph 2, researchers make copies of old stone tools in order to

(A) protect the old tools from being worn out

(B) display examples of the old tools in museums

(D) learn how to improve the design of modern tools

5. In paragraph 2, the author mentions all of the following as examples of ways in which early

stone tools were used EXCEPT to

(A) build home bases

(B) obtain food

(D) shape wood

6. The word innovative in line 13 is closest in meaning to

(A) good

(B) new

(D) costly

7. The word them in line 15 refers to

(A) issues

(B) researchers

(D) specimens

8. The author mentions characteristic chippage patterns in line 16 as an example of

(A) decorations cut into wooden objects

(B) differences among tools made of various substances

(D) indications of wear on stone tools

9. The word extract in line 19 is closest in meaning to

(A) identify

(B) remove

(D) compare

10. The word whether in line 26 is closest in meaning to

(A) if

(B) how

(D) when

托福阅读真题2

PASSAGE 11

Plants are subject to attack and infection by a remarkable variety of symbiotic species and have evolved a diverse array of mechanisms designed to frustrate the potential colonists. These can be divided into preformed or passive defense mechanisms and inducible or active systems. Passive plant defense comprises physical and chemical barriers that prevent entry of pathogens, such as bacteria, or render tissues unpalatable or toxic to the invader. The external surfaces of plants, in addition to being covered by an epidermis and a waxy cuticle, often carry spiky hairs known as trichomes, which either prevent feeding by insects or may even puncture and kill insect larvae. Other trichomes are sticky and glandular and effectively trap and immobilize insects.

If the physical barriers of the plant are breached, then preformed chemicals may inhibit or kill the intruder, and plant tissues contain a diverse array of toxic or potentially toxic substances, such as resins, tannins, glycosides, and alkaloids, many of which are highly effective deterrents to insects that feed on plants. The success of the Colorado beetle in infesting potatoes, for example, seems to be correlated with its high tolerance to alkaloids that normally repel potential pests. Other possible chemical defenses, while not directly toxic to the parasite, may inhibit some essential step in the establishment of a parasitic relationship. For example, glycoproteins in plant cell walls may inactivate enzymes that degrade cell walls. These enzymes are often produced by bacteria and fungi.

Active plant defense mechanisms are comparable to the immune system of vertebrate animals, although the cellular and molecular bases are fundamentally different. Both, however, are triggered in reaction to intrusion, implying that the host has some means of recognizing the presence of a foreign organism. The most dramatic example of an inducible plant defense reaction is the hypersensitive response. In the hypersensitive response, cells undergo rapid necrosis — that is, they become diseased and die — after being penetrated by a parasite; the parasite itself subsequently ceases to grow and is therefore restricted to one or a few cells around the entry site. Several theories have been put forward to explain the basis of hypersensitive resistance.

1. What does the passage mainly discuss?

(A) The success of parasites in resisting plant defense mechanisms

(B) Theories on active plant defense mechanisms

(D) How the immune system of animals and the defense mechanisms of plants differ

2. The phrase subject to in line 1 is closest in meaning to

(A) susceptible to

(B) classified by

(D) strengthened by

3. The word puncture in line 8 is closest in meaning to

(A) pierce

(B) pinch

(D) cover .

4. The word which in line 12 refers to

(A) tissues

(B) substances

(D) insects

5. Which of the following substances does the author mention as NOT necessarily being toxic to

the Colorado beetle?

(A) resins

(B) tannins

(D) alkaloids

6. Why does the author mention glycoproteins in line 17?

(A) to compare plant defense mechanisms to the immune system of animals

(B) to introduce the discussion of active defense mechanisms in plants

(D) to emphasize the importance of physical barriers in plant defense

7. The word dramatic in line 23 could best be replaced by

(A) striking

(B) accurate

(D) appealing

8. Where in the passage does the author describe an active plant-defense reaction?

(A) Lines 1-3

(B) Lines 4-6

(D) Lines 24-27

9. The passage most probably continues with a discussion of theories on

(A) the basis of passive plant defense

(B) how chemicals inhibit a parasitic relationship.

(D) the principles of the hypersensitive response.

托福阅读真题3

PASSAGE 12

Among the species of seabirds that use the windswept cliffs of the Atlantic coast of Canada in the summer to mate, lay eggs, and rear their young are common murres, Atlantic puffins, black-legged kittiwakes, and northern gannets. Of all the birds on these cliffs, the black-legged kittiwake gull is the best suited for nesting on narrow ledges. Although its nesting habits are similar to those of gulls that nest on flat ground, there are a number of important differences related to the cliff-nesting habit.

The advantage of nesting on cliffs is the immunity it gives from foxes, which cannot scale the sheer rocks, and from ravens and other species of gulls, which have difficulty in landing on narrow ledges to steal eggs. This immunity has been followed by a relaxation of the defenses, and kittiwakes do not react to predators nearly as fiercely as do ground-nesting gulls. A colony of Bonaparte's gulls responds to the appearance of a predatory herring gull by flying up as a group with a clamor of alarm calls, followed by concerted mobbing, but kittiwakes simply ignore herring gulls, since they pose little threat to nests on cliffs. Neither do kittiwakes attempt to conceal their nest. Most gulls keep the nest area clear of droppings, and remove empty eggshells after the chicks have hatched, so that the location of the nest is not given away. Kittiwakes defecate over the edge of the nest, which keeps it clean, but this practice, as well as their tendency to leave the nest littered with eggshells, makes its location very conspicuous.

On the other hand, nesting on a narrow ledge has its own peculiar problems, and kittiwake behavior has become adapted to overcome them. The female kittiwake sits when mating, whereas other gulls stand, so the pair will not overbalance and fall off the ledge. The nest is a deep cup, made of mud or seaweed, to hold the eggs safely, compared with the shallow scrape of other gulls, and the chicks are remarkably immobile until fully grown. They do not run from their nests when approached, and if they should come near to the cliff edge, they instinctively turn back.

1. What aspect of the kittiwake gull does the passage mainly discuss?

(A) Its defensive behavior

(B) It interactions with other gull species

(D) Its physical difference from other gull species

2. The word rear in line 2 is closest in meaning to

(A) visit

(B) watch

(D) raise

3. The word scale in line 8 is closest in meaning to

(A) climb

(B) avoid

(D) measure

4. The word immunity in line 9 is closest in meaning to

(A) distance

(B) transition

(D) reminder

5. Why is it difficult for ravens to steal the kittiwakes' eggs?

(A) The kittiwakes can see the ravens approaching the nest.

(B) The ravens cannot land on the narrow ledges where kittiwakes nest.

(D) The female kittiwakes rarely leave the nest.

6. The author mentions that eggshells litter around the nests of kittiwakes in order to

(A) demonstrate that kittiwakes are not concerned about predators

(B) prove how busy kittiwakes are in caring for their offspring

(D) illustrate kittiwakes' lack of concern for their chicks

7. According to the passage , it can be inferred that which of the following birds conceal their

nest?

(A) Bonaparte's gulls

(B) Atlantic puffins

(D) Northern gannets

8. The word it in line 17 refers to

(A) location

(B) edge

(D) practice

9. The word conspicuous in line 18 is closest in meaning to

(A) disordered

(B) suspicious

(D) appealing

10. The phrase On the other hand in line 19 is closest in meaning to

(A) therefore

(B) however

(D) by no means

托福阅读真题2020

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托福阅读真题2020

托福阅读真题2020

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