玻璃结构的无规则网络学说？
参考答案：
玻璃的无规则网络学说是1932年由查哈里阿森提出的，该学说借助于离子结晶化学的一些原则，并参照玻璃的某些性能（如硬度、热传导、电绝缘性等）与相应的晶体的相似性而提出的。像石英一样，熔融石英玻璃的基本结构单元也是硅氧四面体，玻璃被看作是由硅氧四面体为结构单元的三度空间网络所组成的，但其排列是无序的，缺乏对称性和周期性的重复，故不同于晶态石英结构。当熔融的石英玻璃中加入碱金属或碱土金属氧化物时，硅氧网络断裂，碱金属或碱土金属离子均匀而无序地分布于某些硅氧四面体之间的空隙中，以维持网络中局部的电中性。对硼酸盐与磷酸盐玻璃也作了类似的描述。
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| With a group of colleagues, I travelled to the north of Thailand. I loved the heat, the streets, the busy markets and the smell of Thai food. One day, I set off from my _1_ to find a temple that interested me. When I walked past some buildings, I was 2 as I glanced between two unfinished buildings. There, an old woman in 3 clothing lay on the dusty stones. The terrible thought crossed my mind 4 she might be dead. Feeling quite helpless, I 5 her. She looked quite beautiful but very ill. As an instant 6 , I reached into my pocket to find some money. 7 , I pushed it into her hand. It was enough money for her to 8 for a few months. At this moment she opened her large, brown eyes filled with tears and 9 the money I'd given her. I felt like the "kind stranger". 10 a common language, she looked at me with the 11 and pity that could burn into a soul. She 12 pushed back the money. I was left shocked. Her eyes were 13 me. It took at least a kilometre of walking to 14 I was quite the fool. She didn't 15 money. She needed covers, a bottle of water and possibly some human comfort. She was the one to teach me a valuable lesson. That evening, I sat analysing my material version of "_16_". I knew I had to 17 my Western values. This beautiful woman had given me something that I will 18 for the rest of my life. When I look back upon the 19 , I hope my face carries the same wise smile that 20 laughed at me. | ||||
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