TOEFL Speaking Task 3 Sample: The professor gives examples of the effects of elephants on the African grasslands habitat. Using the examples from the talk,explain why elephants are considered a keystone species.

1.子项得分

Delivery: 3 Language Use: 3 Topic Development: 3

2.预估分数

Estimated Score: 23

3.表达

从表达方面来看，这个回答的语言流利度和语速基本一致，偶尔有停顿。为了提高发音的准确性，建议在练习时注意发音和语调。此外，可以尝试减少不必要的停顿，使语言更加流畅。

4.话题发展

从话题发展方面来看，回答内容基本上是连贯和有组织的，观点之间的联系也比较清晰。然而，在提供支持或举例方面还有待加强。建议在练习时尝试更详细地描述听力中提到的例子，以便更充分地支持观点。同时，注意保持回答紧扣题目要求，确保内容的相关性。

5.语言使用

Original Answer: In the lecture, the professor mainly talked about the theory that some species do more than others by providing essential services. Without the influence of these key species, the habitat changes significantly. Scientists refer to this important player in an ecosystem as key store species. To reinforce the theory, the professor gave one example in his speech. The elephants are an important species in African grasslands. But if the elephants weren't there, so pretty soon the grass disappears, trees grow in its plains and eventually the whole grassland changes to forest. Moreover, the elephants have an impact on other animal species in the habitat as well. A lot of animals in this habitat rely on the grasses for food. For example, when the grasses disappear, their food source disappears.

Corrected Answer: In the lecture, the professor mainly talked about the theory the concept ("theory"更多地用于科学理论，而这里更适合用"concept"表示概念) that some species do more than others by providing essential services. Without the influence of these key species, the habitat changes significantly. Scientists refer to this important player in an ecosystem as key store keystone (正确的词是"keystone"，而不是“key store”) species. To reinforce the concept, the professor gave one example in his speech. The elephants are an important species in African grasslands. But if the elephants weren't there, so pretty soon the grass disappears, the grass would disappear, (使用条件句更自然) trees grow in its plains and eventually the whole grassland changes to forest. Moreover, the elephants have an impact on other animal species in the habitat as well. A lot of animals in this habitat rely on the grasses for food. For example, when the grasses disappear, their food source disappears.

Revised Answer (140 words): In the lecture, the professor discussed the concept that some species contribute more to their ecosystems by providing essential services. Without these keystone species, habitats can change significantly. To illustrate this concept, the professor used elephants in African grasslands as an example. If elephants were absent from this ecosystem, the grass would soon disappear, allowing trees to grow in their place and eventually transforming the entire grassland into a forest. Furthermore, elephants also impact other animal species within their habitat. Many animals in this ecosystem depend on grass as a food source; thus, when the grass disappears due to the absence of elephants, these animals lose their primary food source and may be forced to leave or face extinction. This example demonstrates why elephants are considered a keystone species in African grasslands.

6.思维导图

- Concept
  - Keystone species

- Example
  - Elephants in African grasslands
    - Grass disappearance
    - Trees growth
    - Habitat transformation

- Impact on other species
  - Food source loss
  - Animals forced to leave or face extinction

7.关键词