简述电子文件鉴定的具体要求。

Mr. and Mrs. Green lived in a big city, and one summer they went to the country（农村）for their holiday. They enjoyed it very much, because it was a quiet, clean place.

One day they went for a walk early in the morning and met an old man. He lived on a farm, and he was sitting in the warm sun in front of his house. Mr. Green asked him, “Do you like to live in this quiet place?”

The old man said, “Yes, I do,” Mr. Green said, “What are the good things about it?”

The old man answered, “Well, the people here know each other. They often come and visit me, and I often go and visit them. And there are also lots of children here.”

Mr. Green said, “That’s interesting. And what are the bad things?”

The old man thought and thought then said, “Well, the same things, are they?”

小题1:Mr. and Mrs. Green _______ the country very much, because it was a quiet clean place.

A．liked

B．like

C．lived

D．live小题2: One day they _____ for a walk early in the morning.

A．went to

B．went out

C．went up

D．went down小题3: The old man ________ enjoyed the country.

A．too

B．little

C．also

D．quiet小题4: The people in the country are very ________.

A．friend

B．friendly

C．clever

D．careful

– Amazing! You _____ have won the first prize in the national English speech contest!

– I’m lucky that all my efforts have finally paid off.  

A．must

B．may

C．can

D．should

下列常用的调味品中，与水充分混合后不能形成溶液的是（　　）

A．香油

B．食盐

C．味精

D．白醋

2014年，塞尔维亚国家旅游局推出“一战百年纪念游”活动，以铭记历史，反思教训。回望百年前的欧洲，虽已变成一只“火药桶”，但当时引爆这个“火药桶”只是一点“火星”。它就是（）

A.涂油子弹事件

B.国会纵火事件

C.波士顿倾茶事件

D.萨拉热窝事件

以二叉链表为存储结构，分别实现二叉树的下列运算：