【英语时差8,16】旧书为什么变黄（下）

The earliest paper, made of white cotton rags beaten by hand consisted almost entirely¹ of long cellulose fibers². As the demand for paper increased, paper makers³ used chlorine to bleach⁴ colored rags. Later, heavy machinery⁵ made it possible to turn wood into paper pulp⁶. But any chlorine bleach left in the paper eventually turns into hydrochloric acid. And so, too, does the lignin, which holds the cellulose fibers together in wood. Other acid-producing compounds were used to treat the paper, and even air pollution from coal-burning factories increased the acid-content of paper. All that acid breaks the chemical bonds between the cellulose molecules⁷, making the paper brittle⁸ and turning it yellow. Today, many important documents are printed on acid-free paper, but in the meantime, library preservationists are working on ways to save millions of books before the acid in the paper turns them to dust.

1 entirely   

ad.全部地，完整地；完全地，彻底地

参考例句：

• The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
• His life was entirely given up to the educational work. 他的一生统统献给了教育工作。

2 fibers   

光纤( fiber的名词复数 )； （织物的）质地； 纤维，纤维物质

参考例句：

• Thesolution of collagen-PVA was wet spined with the sodium sulfate as coagulant and collagen-PVA composite fibers were prepared. 在此基础上，以硫酸钠为凝固剂，对胶原-PVA共混溶液进行湿法纺丝，制备了胶原-PVA复合纤维。
• Sympathetic fibers are distributed to all regions of the heart. 交感神经纤维分布于心脏的所有部分。

3 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

4 bleach   

vt.使漂白；vi.变白；n.漂白剂

参考例句：

• These products don't bleach the hair.这些产品不会使头发变白。
• Did you bleach this tablecloth?你把这块桌布漂白了吗？

5 machinery   

n.(总称)机械，机器；机构

参考例句：

• Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗？
• Machinery ought to be well maintained all the time.机器应该随时注意维护。

6 pulp   

n.果肉，纸浆；v.化成纸浆，除去...果肉，制成纸浆

参考例句：

• The pulp of this watermelon is too spongy.这西瓜瓤儿太肉了。
• The company manufactures pulp and paper products.这个公司制造纸浆和纸产品。

7 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

8 brittle   

adj.易碎的；脆弱的；冷淡的；(声音)尖利的

参考例句：

• The pond was covered in a brittle layer of ice.池塘覆盖了一层易碎的冰。
• She gave a brittle laugh.她冷淡地笑了笑。