# African crocodiles

- 科目：雅思听力真题（Part 4）
- 考频：中频
- 最近考试：2019.6.1/2006.12.9
- 题目数：10
- 来源页：https://www.yaquan.site/paper/d99869c2-e50d-4d8f-8015-b3ef0956b6b4（在线机考练习与音频请访问该页面）
- 数据更新：2026-10-29

## 题目原文

00:00:01,740 
 Section four. You will hear a lecture about Crocodylus niloticus and its living habits. First, you have some time to look at questions thirty-one to forty. 
 00:00:22,120 
 Now listen carefully and answer questions thirty-one to forty. 
 00:00:58,720 
 Good morning. Today, we will continue our study of Crocodylus niloticus by talking about its living habits. We've already discussed the evolutionary attributes that set it apart from its crocodile relatives. Does everyone remember that? 
 00:01:14,760 
 Yes. It has an extremely narrow snout and three or four rows of protective scales on its back, as compared to two rows on other members of the Crocodylus genus. 
 00:01:25,920 
 Let's take a look at how these carnivorous man-eaters live, where they live, and finally, whether they really deserve their vicious reputation. To start, I'd like to address a great question posed to me by a student during yesterday's office hours. We talked about the distribution of crocodiles in Africa and saw that they are highly concentrated in the south and west of the continent. 
 00:01:50,590 
 This student noticed that on the map displaying the distribution of crocodiles across Africa, there were no crocodiles in the northern region and found no mention in the literature of the existence of crocodiles in the north of Africa. Why might there be no crocodiles in North Africa? Let's save this question for later in the lecture. 
 00:02:12,660 
 To find out more about the social habits of the African crocodile, one researcher named Tara Shine of the University of Ulster in Northern Ireland conducted a survey of the wetlands in Mauritania and received reports of forty-six crocodiles living in one group, or float, as we say when referring to crocodiles. Though the usual number is a little less than half of that. 
 00:02:37,680 
 In general, crocodiles are more highly concentrated in wet, subtropical environments near bodies of water and rich vegetation. 
 00:02:46,890 
 While South American crocodiles thrive in cool rainforests, the African crocodile is more equipped for heat. 
 00:02:54,880 
 Though they can survive at the hot temperatures found in some deserts, they are not equipped to handle dry climates and thus cannot survive in places like the Sahara Desert of North Africa. 
 00:03:06,680 
 As cold-blooded animals, crocodiles' core temperatures fluctuate from their average of thirty-eight degrees Celsius as external conditions change. Thus, they need to avoid extreme temperatures. 
 00:03:20,300 
 Others live an underwater life, keeping a body temperature close to that of the water. 
 00:03:26,660 
 As their own unique method of regulating their body temperatures, some African crocodiles have made dens by digging holes in the ground to provide themselves with a cool, dark place to retreat from the hot African sun. 
 00:03:41,960 
 Speaking of the hot African sun, let's go back to the question asked at the beginning of the lecture. 
 00:03:48,900 
 We know that there used to be crocodiles in northern Africa. Yet today there are none. What are some possible explanations for this? 
 00:03:57,860 
 Some students have suggested that the African crocodile has evolved from a desert creature into a wetland creature, thus causing them to migrate south for more appropriate conditions. 
 00:04:09,820 
 Others presume that the crocodile was hunted out of northern Africa by a fiercer predator. 
 00:04:15,640 
 While these are intelligent guesses, the real story is a little bit different. The key to this migration is that the Sahara Desert did not always cover the north of Africa. About eight thousand years ago, the land was fertile wetlands, perfect for breeding crocodiles. Over time, though, the area dried out and the wetland slowly turned to desert, leading the African crocodile to migrate south to the marshlands they call home today. Some crocodiles did, however, adapt to living in dry conditions. In Mauritania, some crocodiles have learned to survive in an area where they can go up to eight months with no water by spending the driest of times in what's called a torpor or short period of hibernation. 
 00:05:08,060 
 To utilize every bit of rainfall, these desert crocodiles dig underground caves that collect runoff, thus staying cool and hydrated. During the mating period in November and December, males attract females to their viciously protected territory through a number of behaviors that range from snapping their jaws all the way to sending infrasonic pulses through the water. Afterwards, the female digs a hole up to sixty centimeters in depth to store the eggs for an eighty-day incubation period. The female protects these eggs during the period and sometimes even helps crack the eggs with her snout at the end. These teeth-gnashing carnivores are softer than we think. Although these vicious creatures have attacked humans on a few occasions, the residents are not afraid of them. In fact, they show a great deal of reverence towards these wondrous creatures. Some say that crocodiles bring water to their habitat, so if they leave, they will bring the water with them. Obviously, this is not true, but it demonstrates the admiration the inhabiting people have for crocodiles. Generally, crocodiles do not predate on humans. They attack when humans populate the crocodile's habitat, instilling fear and uneasiness in the crocs. Like any other species, crocodiles are known to attack when feeling fear. There's still a lot more to be discovered about the African crocodile. Researchers want to know more about the population size, how many crocodiles inhabit Africa in all, how they form separate floats, et cetera. There is still also much to learn about migration patterns and relations to other populations of crocodiles now found in other parts of the world. Next time, we'll examine a few specific case studies of crocodile populations in southern Africa. 
 00:07:03,880 
 That is the end of section four. You now have half a minute to check your answers.

## 题目与答案

### 31. 31 The student thought there were no crocodiles in Northern Africa because

31 The student thought there were no crocodiles in Northern Africa because

- North Africa contains very little wildlife for the crocodile to prey on
- she found no mention in the literature of their existence there
- there is very little water in North Africa

**答案**：she found no mention in the literature of their existence there

原文定位：This student noticed that on the map displaying the distribution of crocodiles across Africa, there were no crocodiles in the northern region and found no mention in the literature of the existence of crocodiles in the north of Africa

### 32. 32 Generally crocodiles live in groups of about

32 Generally crocodiles live in groups of about

- 20
- 38
- 46

**答案**：20

原文定位：received reports of forty-six crocodiles living in one group;Though the usual number is a little less than half of that

### 33. 33 African crocodiles usually in areas with

33 African crocodiles usually in areas with

- hot and dry climates
- hot and wet rainforest
- warm and wet climates

**答案**：warm and wet climates

原文定位：In general, crocodiles are more highly concentrated in wet, subtropical environments near bodies of water and rich vegetation;While South American crocodiles thrive in cool rainforests, the African crocodile is more equipped for heat

同义替换：「warm」↔「more equipped for heat」

### 34. 34 Crocodiles in dry areas live in caves located

34 Crocodiles in dry areas live in caves located

- underground
- in mountainsides
- underwater

**答案**：underground

原文定位：these desert crocodiles dig underground caves that collect runoff, thus staying cool and hydrated

同义替换：「dry areas」↔「desert」；「live in caves」↔「dig underground caves」

### 35. 35 What change caused changes in crocodile populations in North Africa?

35 What change caused changes in crocodile populations in North Africa?

- They were driven away by a fierce predator
- Crocodiles evolved from desert creatures to wetland creatures
- North Africa used to be wetland but slowly turned to desert over time

**答案**：North Africa used to be wetland but slowly turned to desert over time

原文定位：About eight thousand years ago, the land was fertile wetlands, perfect for breeding crocodiles. Over time, though, the area dried out and the wetland slowly turned to desert, leading the African crocodile to migrate south

### 36. Desert crocodiles sometimes live in places with dry periods that last up to 36_____ months.

Desert crocodiles sometimes live in places with dry periods that last up to 36_____ months.

**答案**：eight

原文定位：In Mauritania, some crocodiles have learned to survive in an area where they can go up to eight months with no water

同义替换：「dry periods」↔「with no water」；「last up to」↔「go up to」

### 37. A hole dug by a female crocodile in which to lay eggs can have a 37_____ of up to 60cm.

A hole dug by a female crocodile in which to lay eggs can have a 37_____ of up to 60cm.

**答案**：depth

原文定位：the female digs a hole up to sixty centimeters in depth to store the eggs for an eighty-day incubation period

同义替换：「lay」↔「store」

### 38. Local people are not 38_____ crocodiles.

Local people are not 38_____ crocodiles.

**答案**：afraid of

原文定位：Although these vicious creatures have attacked humans on a few occasions, the residents are not afraid of them

同义替换：「Local people」↔「residents」

### 39. Crocodiles 39_____ out of fear when humans populate their habitat.

Crocodiles 39_____ out of fear when humans populate their habitat.

**答案**：attack

原文定位：They attack when humans populate the crocodile's habitat, instilling fear and uneasiness in the crocs. Like any other species, crocodiles are known to attack when feeling fear

### 40. Researchers want to study more about population size, 40_____ , and relations to other populations of crocodiles.

Researchers want to study more about population size, 40_____ , and relations to other populations of crocodiles.

**答案**：migration patterns

原文定位：There is still also much to learn about migration patterns and relations to other populations of crocodiles now found in other parts of the world

同义替换：「study」↔「learn」

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