2015年2月3日，英国国会表决同意允许医学界利用3个人的基因共同育子，成为全世界第一个准许“三亲育子”的国家．“三亲育子”技术是将父母细胞核基因与一位妇女捐赠者的健康线粒体结合在一起，引入的基因只占婴儿总基因的0.1%．这项技术旨在防止因线粒体基因缺陷引起的严重遗传疾病．下列相关描述正确的是（　　）

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.

下列各组词语中，没有错别字的一组是（     ）

若不等式x²+ax+1≥0对一切 x∈（0，$\frac{1}{2}$ 成立，则a的最小值为（  ）