The wallet which the writer found______.
A. was empty
B. had some money in it
C. had a few coins and a photograph in it
D. had an old photograph in it
查看答案
在生态因子中，对生物生存和繁殖起关键性作用的主导因子。 [ ]
A. 正确
B. 错误
农业生态系统是一种耗散结构。 [ ]
A. 正确
B. 错误
原生演替的顶级是森林。 [ ]
A. 正确
B. 错误
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