选择短语的适当形式填空 to thrust sth upon sb to be serious about fresh from to be obliged to do sth to make sense to tune up to swell with anger They got together trying ______________ of what had been happening during those hectic days.
【单选题】一个长度为 L 的轻弹簧,将其上端固定,下端挂一个质量为 m 的小球时,轻弹簧的总长度变为 2 L . 现将两个这样的轻弹簧按如图所示方式连接, A 小球的质量为 m , B 小球的质量为 2 m ,则两小球平衡时, B 小球距悬点 O 的距离为 ( 不考虑小球的大小,且轻弹簧都在弹性限度范围内 )( )