下列叙述中正确的是（）
Janeisrestless;sheis_____animportantphonecallfromherparents.
Goodparentshavetheabilitytocommunicatemessagesoflove,trust,andself-worth______theirchildren
Heis______absorbedinhisownthoughtsthatheseemsunawareofwhat'sgoingonintheroom
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()
