Averting such destructive contagion should be the overwhelming priority .
避免这种破坏性蔓延应被当作压倒一切的任务。
However , bad stress can be overwhelming .
然而，坏的压力则是势不可挡的。
So today , when the challenges we face start to seem overwhelming or even impossible let us never forget that doing the impossible is the history of this nation ...... it 's who we are as americans ...... it 's how this country was built .
