问题
(2014·东北三省三校一联)Traffic conditions in Beijing________for decades.At first people only complained about jams during rush hours,but today every hour is rush hour
A:is worsening
B:have worsened
C:have been worsening
D:worsened
B:have worsened
C:have been worsening
D:worsened
正确答案是: