A．offeredB．judgedC．checkedD．wondered
A. offered
B. judged
C. checked
D. wondered
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酸雨是指pH值等于6.0的降水。（）
A. 正确
B. 错误
生物个体、种群和群落都是经典生态学的研究对象。（）
A. 正确
B. 错误
What kind of birds came to the bird houses？
A. Soon robins came to the bird houses.
B. Soon bluebirds built nests in the bird houses.
C. Soon purple martins built nests in the bird houses.
D. Soon baby birds built nests in the bird houses.
休眠是生物抵御不利环境的生理机制。（）
A. 正确
B. 错误
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