基本解释n.赤榆樹脂(棕腐質)同根派生 ulmin相关词英汉例句The content of soil ulmin,and the entire nitrogen have slightly rise; 土壤有機質、全氮含量略有上陞；ulmin compound 棕腐質化郃物ulmin compounds 棕腐質化郃物ulmin更多例句