TOEFL阅读理解真题精选

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托福阅读真题1

Pheromones are substances that serve as chemical signals between members of the same species. They are secreted to the outside of the body and cause other individuals of the species to have specific reactions. Pheromones, which are sometimes called social hormones, affect a group of individuals somewhat like hormones do an individual animal. Pheromones are the predominant medium of communication among insects (but rarely the sole method). Some species have simple pheromone systems and produce only a few pheromones, but others produce many with various functions. Pheromone systems are the most complex in some of the so-called social insects, insects that live in organized groups.

Chemical communication differs from that by sight or sound in several ways. Transmission is relatively slow (the chemical signals are usually airborne), but the signal can be persistent, depending upon the volatility of the chemical, and is sometimes effective over a very long range. Localization of the signal is generally poorer than localization of a sound or visual stimulus and is usually effected by the animal's moving upwind in response to the stimulus. The ability to modulate a chemical signal is limited, compared with communication by visual or acoustic means, but some pheromones may convey different meanings and consequently result in different behavioral or physiological responses, depending on their concentration or when presented in combination. The modulation of chemical signals occurs via the elaboration of the number of exocrine glands that produce pheromones. Some species, such as ants, seem to be very articulate creatures, but their medium of communication is difficult for humans to study and appreciate because of our own olfactory, insensitivity and the technological difficulties in detecting and analyzing these pheromones. Pheromones play numerous roles in the activities of insects. They may act as alarm substances, play a role in individual and group recognition, serve as attractants between sexes, mediate the formation of aggregations, identify foraging trails, and be involved in caste determination. For example, pheromones involved in caste determination include the queen substance produced by queen honey bees. Aphids, which are particularly vulnerable to predators because of their gregarious habits and sedentary nature, secrete an alarm pheromone when attacked that causes nearby aphids to respond by moving away.

1. What does the passage mainly discuss?

(A) How insects use pheromones to communicate

(B) How pheromones are produced by insects

(D) The different uses of pheromones among various insect species

2. The word serve in line 1 is closest in meaning to

(A) improve

(B) function

(D) rely

3. The purpose of the second mention of hormones in line 4 is to point out

(A) chemical signals that are common among insects

(B) specific responses of various species to chemical signals

(D) how insects produce different chemical substances

4. The word sole in line 6 is closest in meaning to

(A) obvious

(B) best

(D) final

5. The passage suggests that the speed at which communication through pheromones occurs is

dependent on how quickly they

(A) lose their effectiveness

(B) evaporate in the air

(D) are produced by the body

6. According to the passage , the meaning of a message communicated through a pheromone

may vary when the

(A) chemical structure of the pheromone is changed

(B) pheromone is excreted while other pheromones are also being excreted

(D) pheromone is released near certain specific organisms

7. The word detecting in line 23 is closest in meaning to

(A) controlling

(B) storing

(D) finding

8. According to paragraph 2, which of the following has made the study of pheromones difficult?

(A) Pheromones cannot be easily reproduced in chemical laboratories.

(B) Existing technology cannot fully explore the properties of pheromones.

(D) Pheromone signals are constantly changing.

9. The word They in line 24 refers to

(A) pheromones

(B) roles

(D) insects

10. The word sedentary in line 29 is closest in meaning to

(A) inactive

(B) inefficient

(D) unbalanced

11. Pheromone systems are relatively complex in insects that

(A) also communicate using sight and sound

(B) live underground

(D) live in organized groups

PASSAGE 95 ABCCB ADBAAD

托福阅读真题2

The Homestead Act of 1862 gave heads of families or individuals aged twenty-one or older the right to own 160 acres of public land in the western United States after five years of residence and improvement. This law was intended to provide land for small farmers and to prevent land from being bought for resale at a profit or being owned by large landholders. An early amendment to the act even prevented husbands and wives from filing separate claims. The West, land reformers had assumed, would soon contain many 160-acre family farms.

They were doomed to disappointment. Most landless Americans were too poor to become farmers even when they could obtain land without cost. The expense of moving a family to the ever-receding frontier exceeded the means of many, and the cost of tools, draft animals, a wagon, a well, fencing, and of building the simplest house, might come to $1,000 — a formidable barrier. As for the industrial workers for whom the free land was supposed to provide a safety valve, they had neither the skills nor the inclination to become farmers. Homesteaders usually came from districts not far removed from frontier conditions. And despite the intent of the law, speculators often managed to obtain large tracts. They hired people to stake out claims, falsely swear that they had fulfilled the conditions laid down in the law for obtaining legal title, and then deed the land over to their employers.

Furthermore, 160 acres were not enough for raising livestock or for the kind of commercial agriculture that was developing west of the Mississippi. The national government made a feeble attempt to make larger holdings available to homesteaders by passing the Timber Culture Act of 1873, which permitted individuals to claim an additional 160 acres if they would agree to plant a quarter of it in trees within ten years. This law proved helpful to some farmers in the largely treeless states of Kansas, Nebraska, and the Dakotas. Nevertheless, fewer than 25 percent of the 245,000 who took up land under the Act obtained final title to the property.

1. Which aspect of the Homestead Act of 1862 does the passage mainly discuss?

(A) How it transformed the western United States into a place of small farms

(B) Why it was an improvement over previous attempts at land reform

(D) How it failed in the largely treeless states of Kansas, Nebraska, and the Dakotas

2. An amendment added to the Homestead Act of 1862 specified that

(A) five years of residence was required for landownership

(B) husbands and wives could not file separate claims

(D) land could not be resold for a profit

3. The word formidable in line 12 is closest in meaning to

(A) obvious

(B) predictable

(D) manageable

4. It can be inferred that the safety valve in line 13 refers to

(A) a new kind of machinery

(B) an alternative for urban workers

(D) a procedure designed to protect workers

5. The word intent in line 15 is closest in meaning to

(A) purpose

(B) power

(D) invention

6. According to the passage , why did the government pass the Timber Culture Act of 1873?

(A) to make larger tracts of land available to small farmers

(B) to settle Kansas, Nebraska, and the Dakotas

(D) to increase the variety of trees growing in the western states

7. The word they in line 23 refers to

(A) larger holdings

(B) individuals

(D) trees

8. According to the passage , how many of the farmers who settled land under the Timber

Culture Act of 1873 received final title to the property?

(A) fewer than 25%

(B) more than 160

(D) 245,000

9. The passage mentions all of the following as reasons the Homestead Act of 1862 did not

achieve its aims EXCEPT:

(A) Most landless Americans could not afford the necessary tools and provisions.

(B) Industrial workers lacked the necessary farming skills.

(D) Homesteaders usually came from areas relatively close to the frontier.

10. Which of the following can be inferred from the passage about the Timber Culture Act of

1873?

(A) It especially helped farmers with large holdings of land.

(B) It was most important to farmers living in states that had plenty of trees.

(D) The majority of farmers did not need the extra 160 acres it provided.

PASSAGE 96 CBCDA ABACC

托福阅读真题3

The Moon, which has undergone a distinct and complex geological history, presents a striking appearance. The moon may be divided into two major terrains: the Maria (dark lowlands) and the Terrace (bright highlands). The contrast in the reflectivity (the capability of reflecting light) of these two terrains suggested to many early observers that the two terrains might have different compositions, and this supposition was confirmed by missions to the Moon such as Surveyor and Apollo. One of the most obvious differences between the terrains is the smoothness of the Maria in contrast to the roughness of the highlands. This roughness is mostly caused by the abundance of craters: the highlands are completely covered by large craters (greater than 40-50 km in diameter), while the craters of the Maria tend to be much smaller. It is now known that the vast majority of the Moon's craters were formed by the impact of solid bodies with the lunar surface.

Most of the near side of the Moon was thoroughly mapped and studied from telescopic pictures years before the age of space exploration. Earth-based telescopes can resolve objects as small as a few hundred meters on the lunar surface. Close observation of craters, combined with the way the Moon diffusely reflects sunlight, led to the understanding that the Moon is covered by a surface layer, or regolith, that overlies the solid rock of the Moon. Telescopic images permitted the cataloging of a bewildering array of land forms. Craters were studied for clues to their origin; the large wispy marks were seen. Strange, sinuous features were observed in the Maria. Although various land forms were catalogued, the majority of astronomers' attention was fixed on craters and their origins.

Astronomers have known for a fairly long time that the shape of craters changes as they increase in size. Small craters with diameters of less than 10-15 km have relatively simple shapes. They have rim crests that are elevated above the surrounding terrain, smooth, bowl-shaped interiors, and depths that are about one-sixth their diameters. The complexity of shape increases for larger craters.

1. What does the passage mainly discuss?

(A) What astronomers learned from the Surveyor and Apollo space missions.

(B) Characteristics of the major terrains of the Moon.

(D) Techniques used to catalogue the Moon's land forms.

2. The word undergone in line 1 is closest in meaning to

(A) altered

(B) substituted

(D) preserved

3. According to the passage , the Maria differ from the Terrace mainly in terms of

(A) age

(B) manner of creation

(D) composition

4. The passage supports which of the following statements about the Surveyor and Apollo missions

(A) They confirmed earlier theories about the Moon's surface.

(B) They revealed that previous ideas about the Moon's craters were incorrect.

(D) They were unable to identify how the Moon's craters were made.

5. The word vast in line 11 is closest in meaning to

(A) special

(B) known

(D) great

6. All of the following are true of the Maria EXCEPT:

(A) They have small craters.

(B) They have been analyzed by astronomers.

(D) They tend to be darker than the terrace.

7. All of the following terms are defined in the passage EXCEPT

(A) Moon (line 1)

(B) reflectivity (line 3)

(D) Maria (line 2)

8. The author mentions wispy marks in line 19 as an example of

(A) an aspect of the lunar surface discovered through lunar missions

(B) a characteristic of large craters

(D) features that astronomers observed to be common to the Earth and the Moon

9. According to the passage , lunar researchers have focused mostly on

(A) the possibility of finding water on the Moon

(B) the lunar regolith

(D) craters and their origins

10. The passage probably continues with a discussion of

(A) the reasons craters are difficult to study

(B) the different shapes small craters can have

(D) some difference in the ways small and large craters were formed

PASSAGE 97 BCDAD CACDC

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