如图所示为一列沿x轴正方向传播的简谐横波在某时刻的波形图，A为沿传播方向上的某一质点（该时刻位于平衡位置），该时刻A质点的运动方向是______（填“向右”、“向左”、“向上”、“向下”）．如果该质点振动的频率为2Hz，则此列波的传播速度大小为______m/s．

Up to now, the two countries          for five years.     [ ]

A. have been in conflict    

B. have come into conflict    

C. came into conflict    

D. are in conflict