题目内容
土壤有机质是指存在于土壤中的所有含碳的有机化合物。主要包括土壤中各种动植物的残体、微生物体及其分解和合成的各种有机化合物质。
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非腐殖质是一些较简单、易被微生物分解并具有一定物理化学性质的物质。如糖类、氨基酸、脂肪酸等,占土壤有机质的20%)~30%。
根据耕层土壤有机质含量，把耕层土壤有机质含量高于20%的土壤称作有机质土壤；把耕层土壤有机质含量低于20%的土壤称为矿质土壤。
Suppose you are Mr. Kevin Lee Smith, Write an e-mail to Mr. Scott Hent showing thanks to his quotation and negotiatingwith him on the price and a free-service contract.From:1To:2Subject: Quotation for 3Date: 4，2010,19:52:59Dear 56 your quotation for personal computers. Since this is a large order, we would like a 10% discount on the price you have quoted. 7, we would like to have a free service contract for one year. If you 8 these terms, we would like to confirm the order and receive delivery next week.910
全面建设社会主义现代化国家的进程分两个阶段来安排:第一个阶段,从( )年,在全面建成小康社会的基础上,再奋斗15年,( )。
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