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【简答题】
有一棵二叉树如下图 所示,分别写出其前序、中序遍历的结点序列。 先序序列( )、中序序列( )。
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举一反三
【单选题】I'm sorry to have you waiting so long for Marcia, and I'm afraid it'll be ten minutes _______ she comes back. [ ]
A.
before
B.
after
C.
until
【单选题】— Could I speak to Miss Smith, please? — ______. She's gone to the post office. [ ]
A.
I'm afraid not
B.
I think so
C.
Certainly you can
D.
I'm not sure
【单选题】— Is Alice still performing？ — I’m afraid not. She is said the stage already as she has gone ab
A.
— Is Alice still performing？ — I’m afraid not. She is said ____ the stage already as she has gone abroad for further study. A．to leave
B.
to have left
C.
to be left
D.
to have been left
【单选题】— I'm afraid I have to leave a little earlier. My mother is ill in bed. — ____ I hope she will be all right soon. [ ]
A.
It's nothing.
B.
Nothing.
C.
I'm sorry to hear that.
D.
So she is.
【简答题】 腭骨可分为 ____ 和 ____ 部。
【单选题】--Will Betty join the talent show on Friday? --I’m afraid she won’t. she is too to act in front of other people.
A.
shy
B.
confident
C.
pleased
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