Some of the most beautiful rivers in the UK are from underground springs, which create perfect conditions for wildlife to live. To understand how healthy the rivers really are, scientists keep watching them for numbers of species (物种) over time. This can show how well a habitat can manage stress such as rising temperatures, reduced rainfall and pollution.

Traditionally, researchers survey rivers by going out themselves and searching for plants, animals or signs of their presence (存在). This method works, but it takes much time and can miss some species not present during the survey. A new project called GeneFlow tries a new technology — environmental DNA (eDNA).

When a species — for example, a fish — moves through the environment, it drops bits of itself all the time, from dead skin cells to faeces (粪便). The DNA in these materials is known as environmental DNA (eDNA). If someone tests a sample (样本) of the water, these pieces of DNA can show the recent presence of the fish, though no fish is seen. This technology allows scientists to find species that we cannot see with our eyes, so that we can learn more about the rivers.

GeneFlow aims to explore the species in 10 rivers across the UK. Beyond information collection, it also aims to connect people with their local rivers. With instructions, members of the public have helped to collect water samples from chosen rivers.

Scientists are still studying the water samples, but the early results are promising: nearly 2000 species have been discovered so far, including protected species such as eels and water voles at many places. Several riverfly species — key signs of water quality — were also recorded.

1.1. What’s the purpose of the first paragraph?

A To list possible dangers to the habitats.

B To describe the rivers’ health conditions.

C To explain the importance of river surveys.

D To introduce some beautiful rivers in the UK.

解析：选C。答案：C 题型：推理判断题 解析：第一段说明监测河流物种，能判断栖息地抗环境压力的能力，引出河流调查的重要性。A 只列举危害，片面；B 没有描述河流健康；D 只是开篇引子，不是段落目的。

2.2. What’s the problem with the traditional method to survey rivers?

A It pollutes the rivers.

B It doesn’t work at all.

C It wastes time finding rivers.

D It can miss hidden species.

解析：选D。2.答案：D 题型：细节理解题 解析：原文This method works, but it takes much time and can miss some species not present during the survey. 传统方法会漏掉隐藏、暂时未出现的物种。A 文中未提及污染河流；B “完全无效” 和原文 works 矛盾；C 不是寻找河流耗时，是勘察物种耗时。

3.3. What is eDNA?

A The DNA of a certain fish in the UK.

B The technology of collecting water samples.

C The technology of preventing water pollution.

D The DNA of species found in the environment.

解析：选D。答案：D 题型：词义猜测 / 概念理解题 解析：文中：生物活动脱落的组织中含有的 DNA，叫做环境 eDNA，即生物留在环境中的 DNA。A 仅指鱼类 DNA，范围太窄；B、C 错误，eDNA 不是采样或防污染技术，是生物 DNA。

4.4. What can we learn about the GeneFlow Project from the last two paragraphs?

A It has found positive results so far.

B It has protected species at many places.

C Its researchers have completed their study.

D Its researchers collected samples in person.

解析：选A。4.答案：A 题型：细节理解题 解析：the early results are promising 初步结果喜人，对应 positive results。B：项目是发现保护物种，不是 “保护” 物种；C 科学家还在研究样本，未完成；D 民众帮忙采集水样，不是研究员亲自采集。