In one activity, children try to get a robot arm to pick up a block and place it in a cup.

VOA: special.2010.07.28

They say it would have caused huge clouds of dust to block sunlight.

VOA: special.2009.01.20

The president said the Treasury Department will do what it can to block the bonuses.

VOA: standard.2009.03.16

And,it is threatening to block what little cross-border traffic exists.

VOA: standard.2010.05.26

Turkey,which hoped to join the European Union, threatened in January to block Nabucco, citing a lack of progress in its talks on EU accession, but on Thursday it voiced full support to the project.

VOA: standard.2009.05.08

The 60-vote advantage is also important because it will make it far more difficult for Republicans to block passage of bills through a filibuster, in which senators tie up the floor in long speeches to prevent a vote.

VOA: standard.2009.06.30