A、The investigation was conducted in an airport. B、People who avoided eye contact turned out to be liars. C、20 people were ident

What is the best way to catch someone who is telling a lie? For a long time, the traditional method of identifying liars was to watch their body language, including facial expressions. What if the person appears to be nervous? Is the person unable to look me in the eye? Is he or she looking around the room? What about other nervous movements? Many people—from parents to police officers and airport security personnel—depend on this method. But does a person’s body and face reveal the truth? Actually, using body language and facial expressions to catch someone in a lie is really hard. And it only works, seemingly, by chance.
    According to a new study carried out by researchers in the United Kingdom, talking is the best way to smoke out a liar. The study found that certain conversation-based techniques can help you recognize when a person is lying to you. Like many methods, this conversation method has a name. It is called Controlled Cognitive Engagement, or CCE for short.[17]The investigation took place at one place where lying can get you into big trouble—an airport. The researchers asked volunteers to pretend they were real passengers and then lie to airport security agents. Some of the agents used spoken conversation-based methods to question these make-believe passengers. Others depended instead on the person’s body language, like lack of eye contact and showing signs of nervousness. The agents talking with the passengers were 20 times more likely to catch the liars. Here are some tips for catching a liar by using the conversational CCE method.
1. Use open-ended questions
    These are the opposite of "Yes" and "No" questions. Open-ended questions force the person to stretch the story of their lies until they get caught in their own web of lies.
2. Use the element of surprise
    Ask questions they may not think you are going to ask. Ask questions that are surprising or off-topic. This will make it harder for them to keep lying. Or better still ask them to re-tell an event backwards in time, going from the most recent event to the earliest. This is hard enough to do with the truth, let alone a story of lies.
3. Watch for changes in confidence and speaking styles
    Liars will often change their speaking style when they are questioned. For example, when they feel in control they may be very talkative. But if they feel they are losing control, they may not talk much at all.
16. What is the best way to catch a liar according to the speaker?
17. What do we learn about the investigation mentioned in the lecture?
18. What does the conversational CCE method include according to the speaker?