若二叉树的先序遍历序列为ABDECF,中序遍历序列DBEAFC,则其后序遍历序列为()。
A.DEBAFC
B.DEFBCA
C.DEBCFA
D.DEBFCA
参考答案:D
In my opinion,life in the twenty-first century is much easier than _______.
A.that used to be
B.it is used to
C.it was used to
D.it used to be
“天道不几顿乎”中的“顿”意思是()
A.整顿
B.安顿
C.疲乏
D.止息
E.倒下