n.半径，有效航程，范围，界限 ‖ radius drill定距射门练习 radius of action滑降弯转半径 radius of burst爆炸半径 radius of damage破坏半径 radius of flight飞行半径 radius of gyration回转半径 radius of influence影响半径 radius of operation活动半径 radius of rotation转动半径 radius of safety安全半径 radius of visibility能见半径