(1)決然と努力する
(2)to strive with determination; "John is bucking for a promotion"
さらに詳しく
(1)素早く軽快な動きで投げ返す
(2)throw back with a quick, light motion; "She tossed back her head"
(1)上部を反対方向へ動かし、下に向ける
(2)move the upper body backwards and down