英语语法分析

Laurionite and phosgenite didn't occur naturally in and around Egypt, but ancient recipes showed that laurionite was synthesised by painstaking procedures, of which phosgenite was a by-product.

羟氯铅矿和角铅矿并非偶然，在埃及附近也没有类似矿藏，一份古配方显示，羟氯铅矿是通过十分复杂的步骤合成出来的，而角铅矿只是其副产物。