floating ice cover的意思|示意

By the beginning of June, the ice cover-as defined by the percentage of ocean covered by at least 15% floating ice-had dropped far below what is usual for the time of year.

6月初，覆冰率(定义为洋面浮冰率15%以上的水域比例)远低于常年水平。

Some polar bears have been seen swimming hundreds of miles from land—though they probably cover most of that distance by floating on sheets of ice.

曾经有人观察到北极熊在水中连续游泳数百英里，当然也许有相当的距离它们是靠借助漂浮的冰面“偷懒”完成的。