51.   The protests have become the most serious challenge to Milosevic in nine years in power, and the Serbian leader faces a tough choice.

52.   The protests have become the most serious challenge to Milosevic in nine years in power.

53.   The protests were becoming increasingly violent, but talks between government officials and community leaders from the Shiite suburbs where the unrest centered has calmed the situation.

54.   The subsequent street protests have become the biggest challenge to Milosevic in his nine years in power.

55.   Though many occupations ended over the holidays, protests have become increasingly violent.

56.   Worker protests have become common in China in recent years as bankrupt state-owned enterprises struggle to pay their work forces.

57.   Worker protests have become common in China in recent years as bankrupt state-owned enterprises struggle to pay their workforces.

58.   With frustrations mounting over the layoffs, protests have become more violent in recent weeks.

59.   Worker protests have become routine, though many strikes and other demonstrations last only for a day and have not crippled any major industries.

60.   Anti-government protests have become a daily event in Argentina, with some of them ending in violence.