Polar bears cannot survive without sea ice, using it to raise their young, to travel and as a platform for hunting seals - their primary food source.

没有海冰，北极熊就无法生存。 它们需要利用海冰来抚养幼仔，四处漫游，并以此为平台捕猎它们的主要食物，海豹。

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At the next stop, Xinran sees the young girl talking to a food seller on the platform and waves goodbye, assuming the family has got off.

在下一站，欣然看到这个年轻的女子和站台上的一个卖食品说着话，并挥手向她道别。欣然猜想这家人已经下车了。

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The train finally arrived and two young men——one big and broad，the other small and slight——stepped onto the platform.

火车终于到站了，两个年轻人——一位，个儿高，体态魁梧；

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Obama on the Foreign Relations Committee and, as a presidential nominee in 2004, gave the young senator a platform on the national stage when he asked him to speak at the Democratic National Convention.

CNN: Obama nominates John Kerry to be secretary of state

But ultimately we provide a platform where young people can express themselves in a non-judgmental environment.

NPR: Acting Students Ready for Their Next Role

The young entrepreneur believes the platform he created will be a game changer because it focuses on peer learning and collaboration.

FORBES: Unishared: Revolution in Online Education Beyond Coursera, Edx, and Udacity