The author includes a discussion of the American black bear, Ursus americanus, most likely
A. provide additional support for the unique feeding habits of bears
B. discount the theory regarding a bear's ability to remain well fed
C. evaluate the dispute between advocates of differing theories regarding bear behavior
D. challenge recent research on the way in which bears secure food
E. suggest further investigation of human interaction with bears
It can be inferred from the passage that which of the following is true of bears？
A. They are particularly resourceful.
B. They must enter human habitats in order to survive.
C. They cannot tolerate human food.
D. They eat voraciously throughout the winter.
E. They have only one method of obtaining food.
假设j表示经济对环境的影响，P表示人口，A表示消费水平，T1表示线性经济的技术，T2表示循环经济的技术，则循环经济的经济方式可用公式表示为()。
A. I＝P×A×T
B. I＝(P×A)／T2
C. I＝(P×A)／T1
D. I＝(P×T2)／A
The author of the passage is primarily concerned with presenting
A. a description of cultural differences
B. an overview of animal behavior
C. a history of international tourism
D. evidence to refute a global theory
E. an account of animal cruelty
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