The major challenge of manufacturing glass of biological origin is that its molecules are thermally unstable and tend to decompose easily at high temperatures.

制造生物玻璃的主要挑战是其分子热不稳定，在高温下容易分解。

The key words are 'when', 'begin' and 'manufacturing glasses' and because the question asks 'when' - you need to listen for a date.

关键词是“何时”、“开始” 和“制造眼镜” ，因为问题问的是“何时” ——你需要听一个日期。

Their studies helped determine that while compounds like borax, hydrated sodium borate, are effective at cleaning, adding minerals to the soil, repealing pests and manufacturing glass and porcelain, they`re less savory as a food preservative.

他们的研究结果显示，尽管硼砂和水合硼酸钠这样的复合物在，清洁，给土壤增肥，驱除害虫，制作玻璃和陶瓷方面有很好的效果，但是作为食品添加剂还是不妥的。