胡敏酸 - 富啡酸比值 HA/FA ratio
土壤腐殖质组成中胡敏酸(碳)量和富啡酸(碳)量之比值。常以表征土壤腐殖质组成和性质。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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