岛屿是由堆积的泥土和杂草以及湖底的物质构成的。

Islands are made from packed earth and weeds and material from the bottom of the lake.

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它们可能看起来漂浮在水面上，但实际上它们一直都能到达湖底。

They may have appeared to be floating in the water, but in fact they reach all the way to the bottom of the lake.

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现在有人担心，计划修建的穿越湖底的输油管道可能会重新造成污染，导致鱼类数量再次下降。

Fears are now being voiced that the planned construction of an oil pipeline across the lake's bottom might revive pollution and cause the fish population to decline again.

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Science can be hands-on, you might be down at the lake picking up algae and studying them or something, that would be hands-on.

科学研究也是要动手的,你可能会到湖底,收集水藻并研究它们,这就是动手操作

耶鲁公开课 - 生物医学工程探索课程节选