机枪每秒钟射出15颗子弹.每颗子弹质量为0.02kg，射出的速率为800m/s，则射击时的平均反冲力大小为()
Goodparentshavetheabilitytocommunicatemessagesoflove,trust,andself-worth______theirchildren
Theblackwriterwantedtheothermembersoftheworkshoptotreat_________asanequal.
v摩尔理想气体压强为p、体积为V，则其温度T为(摩尔气体常数为R)()
两列波的表达式分别为y1=cos2Avtx(/)和y2=cos2Avtx(/)，两波叠加后在坐标原点x=0处的振幅为()
