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3-7How Do Scientists Study Ecosystems? 科學家怎麼研究生態系？
Some Scientists Study Nature Directly
有些科學家直接研究自然

Some Scientists Study Ecosystems in the Laboratory
有些科學家研究生態系在實驗室裏

Some Scientists Use Models to Simulate Ecosystems
有些科學家模仿生態系模型來研究

We Need to Learn More about the Health of the World’s Ecosystems
我們需要學會更多關於世界生態系的健康