1.rucksack  2.blousedback  3.knapsack  

背的英語翻譯：

back
【醫(yī)】 back; dorsa; dorsi-; dorso-; dorsum; noto-; opistho-; tergum

囊的英語翻譯：

bursa; purse; theca; vesica
【醫(yī)】 accessory pocket; bag; balloon; bladder; bursa; Capsul; capsula
capsulae; capsule; cyst; cyst-; cysti-; cystido-; cystis; cysto-
hydatid; kysto-; pouch; sac; sacci; saccus; Ves.; Vesic.; vesica
vesicle; vesico-