把“upon addition of HCl”这种念头掐死。写“滴入盐酸后”就行。“The solution was observed to become turbid”改成“溶液立刻变浑”。删掉所有“it is found that”“it can be seen that”,主语必须是物或人。动词往前顶,少用被动,多用“加入”“析出”“冒出”“褪色”这种带手劲的词。