藏书保护的任务是什么？
参考答案：
保护藏书的安全，延长其使用寿命，保证完整而长久地为读者利用。
哺乳动物的骨在_________的牵引下，围绕着_________运动，使躯体完成各种动作。
_____ the burden of carrying heavy school bags, some schools introduced iBooks a few weeks ago. [ ]
A . Eliminating
B. Eliminated
C. To eliminate
D. Having eliminated
