英语语法分析

Limonene needed in recycling foamed polystyrene was extracted from the ear of schizonepeta tenuifolia using ligroin.

本文研究从荆芥穗中提取回收聚苯乙烯所需的柠檬烯，其方法是溶剂萃取。

After ethanol precipitation, OPC was separated by ethyl acetate-ligroin system. Content of OPC was determined by normal butyl alcohol-hydrochloric acid method at 546 nm to be over 90%.

提取物经醇沉后，用石油醚沉淀法分离低聚原花青素，产物经正丁醇-盐酸法显色，比色法测定质量含量可达90%以上。