Anti-Maduro protests persist in Venezuela, policeman shot dead

By Andrew CawthorneCARACAS (Reuters) - Opponents of President Nicolas Maduro staged sit-ins and roadblocks across Venezuela on Monday to press for elections, sparking new unrest that killed a policeman.Demonstrators have been on the streets daily since early April to demand elections, freedom for jailed activists, foreign humanitarian aid to offset an economic crisis, and autonomy for the opposition-controlled legislature.Maduro accuses them of seeking a violent coup.