Narrator: Listen to part of a lecture in an environmental science class. Professor: So, we've been talking about renewable energy sources, and today I want to focus on a less familiar one: tidal energy. Unlike solar or wind, tidal energy is predictable because it depends on the gravitational pull of the moon and the sun, which we can calculate precisely. However, there are significant challenges. First, the infrastructure, like underwater turbines, is expensive to install and maintain due to corrosive saltwater. Second, tidal energy is only viable in locations with a large tidal range, typically over five meters, which limits its application to about forty coastal sites worldwide. But there's another issue: environmental impact. Turbines can harm marine life, particularly fish and mammals that swim through the blades. Some designs are trying to mitigate this by slowing blade rotation or using enclosed systems, but these often reduce efficiency. So, while tidal energy offers a steady, clean power source, its high costs and ecological trade-offs mean it's not yet a silver bullet for our energy needs. Now, any questions so far?
❓ Question What is the professor's main point about tidal energy?
A. It is a promising renewable source that is now widely deployed.
B. Its predictability makes it superior to all other renewable sources.
C. Despite its benefits, high costs and environmental issues limit its use.
D. The main problem with tidal energy is its dependence on weather conditions.
✅ Correct Answer
Despite its benefits, high costs and environmental issues limit its use.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word
