firs[计] 先前的firn.枞树；冷杉；枞木firing silver paste烧银点firing top-centre点火上死点firing optimization燃烧调整fir tree connection枞树形叶根固定firing accuracy test射击精度试验firing time sequence发射时序firing point shelter射击处遮屏fir-fighting fleet消防舰队, 救火舰队Firing effectiveness射击效能firing system tester点火系统试验器