knapsackn.背包knapsack power duster背负式动力喷粉机knapsack type sprayer背负式喷雾器Knapsack cryptosystem背包体制knapsack mist sprayer背负式弥雾器knapsack mist-duster背包式喷粉机knapsack power mistduster背负式动力弥雾喷粉机knapsack sprayer-duster背负式喷雾喷粉机knapsack public key cipher肯包公钥密码knapsack pubic-key system背包公钥密码体系knapsack lever type sprayer背负式杠杆喷雾机