用“样方法”调查蒲公英种群密度的过程是①选取一个该种群分布比较均匀的长方形地块，将该地按照长度画成10等份，在每份的中央划一个大小为1m2的样方②选取一个该种群分布比较密集的长方形地块，将该地按照长度

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用“样方法”调查蒲公英种群密度的过程是
①选取一个该种群分布比较均匀的长方形地块，将该地按照长度画成10等份，在每份的中央划一个大小为1m²的样方
②选取一个该种群分布比较密集的长方形地块，将该地按照长度画成10等份，在每份的中央划一个大小不同的样方
③计数每个样方内该种群数量，取其最大值作为种群密度的估计值
④计数每个样方内该种群数量，取其平均值作为该种群密度的估计值

A：①③

B：①④

C：②③

D：②④

上一题下一题 0.0难度选择题更新时间:2018-10-19 02:51:50

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B

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阅读理解
(Mr. Zhang is showing Wei Fang and Li Lei a modern factory.)
Mr. Zhang: You can’t see many workers here, but you can see a lot of robots. Look, that robot has two big hands.
Wei Fang: How strong it looks!
Mr. Zhang: Yes. It does much work for us.
Li Lei: There are so many big boxes here. What are the robots doing?
Mr. Zhang: They are making fridges.
Wei Fang: How fast they are working!
Li Lei: How much time do they need to make a fridge, Mr. Zhang?
Mr. Zhang: About five minutes.
Wei Fang and Li Lei: Only five minutes! What a modern factory it is!

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