firs[计] 先前的firn.枞树；冷杉；枞木firing technique点火技术firing equipment加热设备firing capacitor点火电容器firing stability射击稳定性firing precision射击准确度firing mechanism击发机构,发火机firing J-Horner射击调平装置firing employment火力运用firs round attack第一回合进攻firing dispersion密集度