She had to concentrate on flexing her pectoral muscle, or the triceps, to power the arm.
She had to concentrate on flexing her pectoral muscle, or the triceps, to power the arm.
为了给手臂提供力量，她不得不用力伸缩她的胸肌或者三头肌。
She had to concentrate on flexing her pectoral muscle, or the triceps, to power the arm.
为了给手臂提供力量，她不得不用力伸缩她的胸肌或者三头肌。