We never dared to ask him a question, _______?

We never dared to ask him a question, _______?A.did we B.didn’t we C.dared we D

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_______ come into leaf or bloom is obviously a sign of spri

_______ come into leaf or bloom is obviously a sign of spring.A.Trees B.The tre

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种群的基本特征有哪些方面?

种群的基本特征有哪些方面?

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生态系统的发展趋势是净生产量加大。(  )

生态系统的发展趋势是净生产量加大。(  )

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一片农田弃耕后,依次被杂草、灌丛乃至森林替代的过程属于(  )

一片农田弃耕后,依次被杂草、灌丛乃至森林替代的过程属于(  ) A.原生演替 B.次生演替 C.逆行演替 D.水生演替

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