A:Sorry, he is busy at the moment.
B:Why didn't you call earlier?
C:Certainly. May I know your name?
D:Sorry, he doesn't want to see you.
在“活性炭、碳酸钙、食醋、钛合金、聚乙烯、甲烷”中选择适当的物质填空:
小王分别从以下四种土壤环境取样探究土壤动物丰富度。推测土壤动物丰富度最高的样品来自( )