听力音频：
L1：
讲座
1. What is the main focus of the lecture
How the economic worth of trees in urban settings is determined
How urban planners determine which trees are the most beneficial to cities
Why some cities do not plant many trees
Where trees can make the greatest economic impact in urban areas
2. What does the professor imply about the practice of assigning a monetary value to trees
It has motivated residents in some cities to plant a large number of trees.
It has not yet been shown to have a positive economic impact on cities.
It is motivated by the need to make decisions about spending money on planting or maintaining trees.
It is a practice that involves too many factors for the result to be meaningful.
3. What does the professor say about the sales comparison approach
Its results depend on the appraisers involved.
Appraisers do not like it.
Few cities use this approach.
It is an outdated approach .
4. A student mentions that trees can save energy by providing shade. What other benefits does the professor mention that can be accounted for in the benefit-based approach（多选题）
Reducing the amount of pollution in the air
Helping to decrease flooding
Making streets more attractive for retailers
Reducing the costs of repairing pavement
5. Why does the man talk about the length of time it takes for a tree to grow
To explain why he thinks that tree maintenance is important to the benefit-based
approach
To suggest why the sales comparison approach is preferable to the benefit-based approach
To raise a question about the accuracy of the benefit-based approach in determining the monetary value of trees
To explain why foresight is needed to create an urban forest
6. What does the professor say about the social benefits of trees
They are less important than other benefits.
They can be difficult to quantify.
They have only recently been acknowledged by city planners.
They are more obvious to most people than are other benefits of trees
