设a>1>b>-1,则下列不等式中恒成立的是 (    )

完形填空

　  It was not until books were produced that knowledge really    1   quickly around the world.

      For centuries, books were rare and very    2  . Each one was written    3     ! So it is understandable that one book took many months   4 . Today, a printer can produce    5    books in a day. Instead of being expensive, books these days are light, cheap and easy to get hold of. However many of these books are    6    ancient to be held and studied by many people. They need to be kept     7 away from danger. So here in the British Library, the latest technology has  8 download pages of these books onto a computer. This system has been developed   9     readers will be able to touch, read and study these beautiful ancient books. Have a look at the screen here. It is possible   10    the pages of the book, just as you would turn a normal book, by pressing a button. And on this part of the screen, helpful information about the book is displayed.

8的立方根与4的平方根之和是（　　）