有效的捕食可能把猎物种群消灭，然后捕食者也因饥饿而死亡。()
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当生物种群数量达到高峰时，由于种群压力增加，种群数量会趋于下降。这是自然对生物种群的调节。()
A. 正确
B. 错误
What's the purpose of the stress management courses that runs by Jane Collard？
A. Help people reduce their stress.
B. Make the trainees realize stress in itself is not harmful.
C. Stress enables people to feel motivated and to perform. effectively.
D. A complete absence of stress can lead to depression.
Which of the following can best summarize the passage？
A. Stress are not always harmful.
B. Stress is becoming an increasingly common feature of the workplace.
C. Jane Collard's research on stress.
D. How to prevent stress？
Where can ozone be found useful to life according to the passage？
A. Between ten and fifty kilometers up in the atmosphere.
B. In the far sky.
C. Near the sun.
D. Far from the sun.
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