guard arm

例句：

1. 1. The soldier stood guard at the gate with his arms crossed.
   士兵双臂交叉站在门口站岗。
2. 2. She held her son's hand as he walked across the stage, her protective arm around him.
   她牵着儿子的手，他走过舞台时，她的保护性手臂搂着他。
3. 3.The policeman stood guard outside the building, ready to intervene if needed.
   警察站在大楼外警戒，随时准备介入。