【英语时差8,16】旧书为什么变黄（上）

Open an older book and you may find the paper yellowed around the edges. Even older books fall apart as you turn the pages. But you might be surprised to learn that the pages in some of the oldest books are still white and turn easily without cracking. During the last 500 years, the quantity of paper being produced has increased dramatically, but the chemical composition of modern paper causes it to turn yellow and crumble¹ faster. Paper can be made from almost any form of cellulose that can be shredded² into tiny fibers³ and mixed into a watery⁴ pulp⁵. Since cellulose is found in all plants, most plant matter can be used to make paper. In the pulp, the cellulose fibers are partly dissolved so that when the sheet of paper is dried, the molecules⁶ of different fibers bond to each other.

1 crumble   

vi.碎裂，崩溃；vt.弄碎，摧毁

参考例句：

• Opposition more or less crumbled away.反对势力差不多都瓦解了。
• Even if the seas go dry and rocks crumble,my will will remain firm.纵然海枯石烂，意志永不动摇。

2 shredded   

shred的过去式和过去分词

参考例句：

• Serve the fish on a bed of shredded lettuce. 先铺一层碎生菜叶，再把鱼放上，就可以上桌了。
• I think Mapo beancurd and shredded meat in chilli sauce are quite special. 我觉得麻婆豆腐和鱼香肉丝味道不错。 来自《简明英汉词典》

3 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。

4 watery   

adj.有水的，水汪汪的；湿的，湿润的

参考例句：

• In his watery eyes there is an expression of distrust.他那含泪的眼睛流露出惊惶失措的神情。
• Her eyes became watery because of the smoke.因为烟熏，她的双眼变得泪汪汪的。

5 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。

6 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。