Listen to part of a lecture in an environmental science class.
Professor: Today we're going to discuss a concept that often surprises people: the idea that some types of pollution can actually be beneficial in certain contexts. I'm not talking about chemical spills or smog, of course. I'm referring to nutrient pollution, specifically nitrogen and phosphorus runoff from agricultural areas. While these nutrients are essential for plant growth, when they enter aquatic ecosystems in excess, they can cause what we call eutrophication. This process leads to rapid algae growth, which then decomposes and depletes oxygen in the water, harming fish and other organisms. However, in some nutrient-poor coastal regions, small, controlled additions of certain nutrients might stimulate phytoplankton growth, which forms the base of the marine food web. This could potentially increase fish populations. But we must be cautious—the risks of uncontrolled nutrient loading far outweigh any potential benefits. In fact, many estuarine systems have collapsed due to excessive nutrient input, creating dead zones. So, while the idea is intriguing, it's not a practical solution for most areas.
❓ Вопрос What is the professor's main point about nutrient pollution?
A. It is always harmful and should be completely eliminated.
B. It may have limited beneficial effects but is generally too risky to use as a solution.
C. It is more dangerous in agricultural areas than in coastal regions.
D. It can be effectively managed by adding more nutrients to the water.
✅ Правильный ответ
It may have limited beneficial effects but is generally too risky to use as a solution.
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