一个同学站在平面镜前1米处，然后他以1.2米/秒的速度远离平面镜，5秒后镜中的像与平面镜相距____m； 另一同学用毛皮摩擦过的橡胶棒接触验电器的金属球，发现金属铂片张开一定的角度，其原因是____．

如图，在四棱锥P﹣ABCD中，PA⊥平面ABCD，四边形ABCD为正方形，AB=PA=4，A点在PD上的射影为G点，E点在AB上，平面PCE⊥平面PCD．

右图记载的是中共建军史上最早的阅兵式情景，摄于一九三一年十一月初。这次阅兵是为了 
                

根据句子意思, 从方框中选择恰当的短语填空。

To my surprise;   has a lasting value;   in all directions;   broke out       were forced to ;     out of breath ;    gives up; take notice of;     directed;     playing ;      showed an interest in

Chinese Premier Wen Jiabao, in_________ interview with Hong Kong reporters on April 13, said that Chinese economy in ________ first quarter showed signs of better than expected positive changes.