题目内容：

    Reading body language to know if a person is lying applies not just to ordinary people but even to professionals, as well. The police use it to be sure whether the person is guilty of a certain wrongdoing（坏事） or not, teachers employ it to find out if a child really has or hasn’t done his or her homework and parents apply it to find out if their teenagers really did go to a group study meeting as they said they would.

In the past, it seemed like reading body language to judge guilt may not have been in effect, at least in some cultures. Tribal groups of centuries used to figure out if a native committed a crime (犯罪) using pain tests, such as dipping a hand in boiling water, walking on burning coals, and others.

For example, a native whose hand came out burnt after a dip in boiling water is considered guilty at the time. Luckily, no such judging process exists any more and we have the chance to explain ourselves by appearing in court and giving our statements. However, it may not be easy either, because it requires knowledge of reading body language.

How can you tell if the other person is lying through his teeth? There are several ways to tell. One is when the other person is unable to look at you in the eyes as he tells a lie. Thus, if you ask your partner if he has been cheating on you, you will know that something is wrong if he says he hasn’t but looks elsewhere while he says so.

1.Why did the writer mention the police, teachers and parents?

A.To show all the people who read body language can know if a person is lying.

B.To show they are doing different kinds of jobs.

C.To show police are much cleverer than teachers and parents.

D.To show all of them can read body language.

2.How did tribal groups find out if a native committed a crime several hundred years ago?

A.By being decided by their leaders.

B.By using pain tests.

C.By appearing in court.

D.Through his teeth.

3.The passage mainly tells us ______________________.

A.we can catch a liar （说谎者） by body language

B.the importance of body language

C.how we should use body language

D.the history of body language being used