running back

running-back的词性：
n.Football （名词）【橄榄球】

1. An offensive back, such as a fullback or halfback, who is designated the responsibility of advancing the ball by running with it on plays from the line of scrimmage.
带球跑动进攻的后卫：具攻击性的后卫或前卫，被指定负责将球从对抗线跑动往前带