他们的遗体堆积在湖底，然后被粘土和淤泥覆盖。

Their remains accumulated on the floor of the lake and were then covered by clay and silt.

youdao

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.

youdao

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.

youdao

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