knapsackn.背包knapsack compressed air type背负式气动喷雾器knapsack pest control machine背负式除虫器knapsack public-key encryption背包公钥加密系统knapsack sprayer with piston pump背负式活塞泵喷雾器knapsack duster with engine drive发动机驱动背负式喷粉机Knapsack public-key cryptosystem背包公钥密码knapsack public- key cryptosystem背包公钥密码体制knapsack compressed air type sprayer背负式气力喷雾机,背负式压气喷雾机knapsack sprayer with pressurized cylinder背负式压力筒喷雾器