【课文讲解】
Key structure
背熟1：It has never been explained why university students seem to enjoy practical jokes more than anyone else.
Eg: It has never been explained why he seems to enjoy doing it.
specialize in. 专门研究
Eg: He specialized in biology after graduation.
背熟2： Inviting the fire brigade to put out a nonexistent fire is a crude form of deception which no self-respecting student would ever indulge in.
except the victims / but the victims
tear up == destroy
take sb seriously 严肃对待
be to do 结构含义：
1. should
Eg: Such a private thing should be avoided.
Such a private thing is to be avoided
2. must
Eg: No students must leave school without the permission of the police.
No students are to leave school without the permission of the police.
3. intend 意图，打算
Eg: We intend to start work next week.
We are to start work next week.
L40-01 end 18’45”
L40-02 begin 10’19”
背熟4：Both the police and the workmen were grateful to the student for this piece of advance information.
be grateful to sb. for sth.
that went on == that happened
背熟5：he threatened to remove them by force.
背熟6: The workmen told him to do as he pleased and the policeman telephoned for help.
as he pleased 随他的意愿做
four more == another four
as this 听到
At the words,he got angry.
With the words, he left the room angrily.
背熟7：At this, the police pointed out ironically that this would hardly be necessary as the men were already under arrest.
pointed out ironically 讽刺地指出
hardly be necessary 大可不必
under 与名词搭配表示一种被动的概念
under discussion / arrest / repair