The river bottom shelves here.

河底从这里呈缓坡倾斜。

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When he was forced to turn sharply to avoid a floating tree branch, the elephant dropped the hat and it fell to the river bottom.

当大象被迫急转弯以避开一根漂浮的树枝时，帽子掉了下来，掉到了河底。

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In that year "a defect at the dam opened the gates, making a toxic layer of hard metals deposited at the bottom of the river come up" to the surface, she said.

就是那年，大坝的门户错误的打开，使得那些原本位于河流底部的有毒重金属层浮到了表面，她继续说道。

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Mr. Aguilar eventually pulled a young gator from the river bottom, and I snapped a photo.

WSJ: Nicaragua's San Juan River by Boat

PCBs are now embedded at the bottom of the river, getting buried under more and more mud as time goes on.

FORBES: Fact and Comment

Higgins also said Sunday that divers were unable to get to what is apparently the jet's left engine on the river bottom.

CNN: Recorders recovered from Hudson in 'excellent' condition