1托福TPO阅读55文本:How Herding Can Provide Safety

In open grasslands there is no place for a large animal to hide.I Thus awatchful grazing animal will see the slight movement that betrays the presenceof a predator long before it is close enough to launch an attack. lt sounds asthough the hunters (predators)stand no chance at all. Unfortunately forthe grazers, life is not so simple, however.I A grazing animal must lowerits head and look at the ground to feed.I lts attention may be occupied foronly a few seconds before it raises its head and resumes its watch whilechewing the food it took: but hunters are patient and skillful and areconcentrating intensely. Those few seconds provide time enough to advance afew steps and then freeze,body flattened against the ground.lt may takehours: but eventually these repeated small advances will put the hunter withinrange-close enough to outrun its prey and the long time the hunt has takenwill have been worthwhile,because the resulting feast will be highly nutritious.Clearly the grazers are at a disadvantage,because while they eat they arevulnerable to attack. The hunters also have a weakness, however: and it isone that allows the grazers to survive. Hunters can attack only one prey animalat a time. This applies even to the predators that hunt as a team, such aslionesses, wolves, and hunting dogs. Their hunt involves running down orambushing an individual. Teamwork allows them to hunt animals much biggerand stronger than themselves and to hunt more successfully,' but it does notallow them to attack more than one individual at a time.

The grazers exploit this weakness by making it as difficult as they can for thepredators to choose an individual as a target. They do not graze alone:scattered widely across the landscape, but together as a herd. Theapproaching hunter sees not a solitary animal, but a crowd of animals, all ofthem moving, so they are constantly crossing and recrossing each other'spaths. No sooner does the hunter choose an individual than another animalhas crossed in front of it and the target has disappeared into the herd From thehunter's point of view this is highly confusing behavior- as, indeed, it is meantto be.

There is another advantage to the grazers: A herd is much more alert than asolitary animal. An animal has to relax its guard while it is taking food; but in aherd there are at any time some animals with their heads down, biting, andothers, with their heads up, watching. What is more, those with their heads upare looking in different directions so that together they are alert to anymovement anywhere on the landscape around them. There is no way for ahunter to approach a herd unobserved. When a member of the herd spotstrouble, it starts to move away. Other members of the herd move with it andthe entire herd starts to move. If the trouble is serious and close, the herd willrun. The individual raising the alarm is simply protecting itself but in doing so itis warning all of the others.

Herding is highly successful, provided members of the herd stay together in atight bunch. The hunter moves with the herd: watching for an individual towander away from the others. When that happens, it tries to move betweenthat individual and the rest of the herd, preventing it from rejoining. Once it hasdone that the hunter has a good chance of making a kill. If the herd starts torun, a solitary hunter may abandon the chase: but a pack of wolves or huntingdogs will regard the running herd of animals as an opportunity and set off inpursuit. As the herd runs, one or two old or sick animals, or young animals thatbecome separated from their mothers, may fall behind.

As soon as the hunter or hunters seize their prey, they lose interest in all othergrazers since then they, too, must concentrate on eating, at which point theherd stops running, those who were left behind rejoin the group: and they allresume grazing.

2托福TPO阅读55文本试题如下：

29. The word slight in the passage is closest in meaning to

A. hidden

B. slow

C. distant

D. small

Paragraph 1

30. According to paragraph 1, which of the following presents a seriousdifficulty for the predators that hunt animals grazing in grasslands?

A. It is difficult to find grazers in grasslands when they are feeding with theirheads down.

B. Predators lack places to hide from prey in grasslands.

C. It is difticult for predators to outrun grazers on grasslands.

D. Grazers in open grasslands tend to be very large animals.

Paragraph 1

31. Which of the following can be inferred from paragraph 1 aboutgrazinganimals?

A. They spend significantly more time looking down at the ground than they dowith their heads raised

B. They tend to remain within a relatively small area for extended periods oftime.

C. They are extremely difficult for predators to see as long as they remainmotionless.

D. They can run signiticantly faster than most of their predators.

Paragraph 1

32. According to paragraph 1, how can a predator get close enough to agrazing animal to launch an attack?

A. By crawling steadily forward with its body pressed to the ground

B. By moving very quickly and surprising its prey

C. By moving forward only when the grazer is taking food from the ground

D. By hiding in the grass and waiting patiently for its prey to move within range

Paragraph 1

33. According to paragraph 2, what is an advantage to predators that hunt asateam?

A. A team can kill animals that are much bigger and stronger than any of thepredators could take on by itself.

B. A team can ambush their prey without having to run them down as anindividual predator has to do.

C. A team can attack more prey animals at one time than an individualpredator could.

D. A team is less vulnerable to an aggressive response from grazers.

Paragraph 2

34. In paragraph 2, why does the author describe the hunting technique usedby predators that hunt as a team?

A. To explain why predators that hunt as a team wait until grazers start eatingto attack

B. To argue that species that hunt as a team do not have the same weaknessas individual predators

C. To emphasize that even predators that hunt in groups cannot hunt andattack more than one prey at a time

D. To help explain why grazers are at a particular disadvantage with certainpredatory animals

35. The word approach in the passage is closest in meaning to

A. come nearer to

B. drive apart

C. attack

D. pursue

Paragraph 4

36. Which of the following is NOT mentioned in paragraph 4 as a way in whichanimals that graze as a herd benefit?

A. Some animals in the herd will be in a position to observe danger whileothers have their heads down.

B. Each animal in a herd tries to protect the others from danger.

C. As a herd, animals can observe the landscape in a variety of directions atonce.

D. The movement of any animal away from potential trouble warns all of theother animals within the herd.

37. The word provided in the passage is closest in meaning to

A.if

B. because

C. unless

D. therefore

Paragraph 5

38. According to paragraph 5, any member of a herd is most at risk frompredators when

A. it is very young

B. it becomes separated from the others

C. the herd includes relatively few old or sick animals

D. the herd begins to runParagraph 5

39. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning inimportant ways or leave out essential information.

A. The hunter or hunters are interested only in seizing their prey and not in anyof the rest of the grazers in the herd.

B. Because the hunters must concentrate on eating once they make a kill, therest of the herd can then stop running and resume grazing.

C. Once the hunters finish eating their prey, they lose interest in the rest of theherd that was left behind.

D. Because they must also concentrate on eating, herd animals resumegrazing as soon as the hunter or hunters seize their prey.

Paragraph 6

40. Look at the four squarest [ ]that indicate where the following sentencecan be added to the passage.

This is because grasslands lack the trees and heavy bush to provide cover foranything but very small animals.

Where would the sentence best fit?

Click on a square [ ] to insert the sentence in the passage

41. Directions: An introductory sentence for a brief summary of the passage isprovided below. Complete the summary by selecting the THREE answerchoices that express the most important ideas in the passage. Some answerchoices do not belong in the summary because they express ideas that are notpresented in the passage or are minor ideas in the passage This questions isworth 2 points.

Grazing in a herd rather than as solitary individuals decreases the risk tograzers from predators.

Answer Choices

A. If a grazer can spot a predator before it actually attacks, the grazer has avery good chance of getting away and since grasslands provide lit cover forpredators, the grazer always has the advantage.

B. Hunters can attack only one grazer at a time: and where there are manyanimals moving back and forth and grazing together in a herd, it is difficult forhunters to maintain their focus on a single target.

C. When a member of a herd wanders away from the others or falls behind asthe herd runs from danger, a hunter who manages to get between it and theherd stands a good chance of making a kill.

D. A grazer cannot watch for danger while feeding, so predators can use thosemoments gradually to approach a solitary animal unobserved; but in a herdthere will always be some animals on alert.

E. When a herd of grazers spots the approach of a solitary hunter: it may runtoward the hunter , which generally causes it to abandon the chase, butpredators hunting as a pack are not so easily driven away.

F. After a herd of running animals sees that the hunters pursuing it havestopped, the herd tries to help members of the group that were left behind.

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