"The ambiguity that's in those answers is very,very difficult for humans to understand, never mind a computer to understand.

VOA: special.2011.02.28

But protecting plants and trees in the garden may not be too difficult if you follow a few suggestions.

VOA: special.2010.01.12

The objects in the exhibit tell a story about government expansion during a difficult period in American history.

VOA: special.2009.01.02

Others disagreed. In any case, it was not a good time to argue it was the Great Depression, and times were difficult.

VOA: special.2009.12.29

But they say finding injured birds in the huge spill and sending out boats to rescue them will be a difficult job.

VOA: special.2010.05.04

President Obama also spoke about the difficult time people in the Gulf area were going through as a result of the oil spill.

VOA: special.2010.06.18

The Democratic Party had a much more difficult time choosing a candidate for president in eighteen sixty-eight.

VOA: special.2010.02.11

So they quickly passed a bill that made it much more difficult for Chinese citizens to come to live in the United States.

VOA: special.2010.03.11

She was never willing to leave a problem unfinished, even difficult problems in mathematics.

VOA: special.2009.11.08

Officials would order all lights in a city turned off to make it difficult for enemy planes to find a target in the dark of night.

VOA: special.2009.11.15

It was difficult to get a true picture of what was happening in Cuba.

VOA: special.2010.07.08

"Many mothers deliver at home in sub-Saharan Africa and it's very difficult for them to get to a hospital or clinic which may be miles away in that time period.

VOA: special.2010.05.24

He also faced a difficult situation in his personal life.

VOA: special.2009.04.23

And he is praising four committees in Congress for agreeing on what he calls "a difficult and complex challenge."

VOA: standard.2009.08.08