化学修复实施周期短,可用于处理各种污染物,但是处理工程大,成本高。()
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疾病与假设病因之间的联系可以是直接的,也可以是间接的。
已知一棵树的前序遍历为ABDEGCF,中序遍历为DBGEACF,求这棵树的后序遍历。(字母和字母之间不要有空格) The preorder sequence of a tree is ABDEGCF, and its infix order sequence is DBGEACF, please write down its post order sequence. (There is no blank space between letters)