Nobody knows for certain what caused the disaster for sure, therefore there's no way of preventing it from happening again, on the same rail road or on other lines around the country.

没有人确切地知道到底是什么造成的灾难是肯定的，所以没有办法防止它再次发生在同一轨道路或其他线全国各地。

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He also mocked Trump for telling jurors he never took notes of business meetings and so couldn't say for sure when certain decisions were made and by whom.

WSJ: Talk of lies, pride as Trump case goes to jury

That's a key element to be sure that even inside the countries they have a certain space for the assistance and protection of the population who could not escape the conflict.

BBC: Viewpoint: 'Our concerns are the civilians'

If, in fact, certain areas of a city are growing, how do you make sure that it still has housing for longtime residents who may not be able to afford huge appreciation in property values?

WHITEHOUSE: President Obama Speaks to Town Hall Meeting at University of Maryland | The White House