Although "lie detectors" are widely used by governments, police departments and businesses

Although "lie detectors" are widely used by governments, police departments and businesses, the results are not always accurate. Lie detectors are commonly【C1】______as emotion detectors, for their aim is to【C2】______bodily changes that contradict what a 28 says. The lie detector records changes【C4】______heart rate, breathing, blood pressure, and the electrical【C5】______of the skin. In the first part of the【C6】______, you are electronically connected to the ma chine and【C7】______a few neutral questions("what is your name？" etc). Your physical reactions serve【C8】______the standard for evaluating what comes【C9】______. Then you are presented with a few【C10】______questions among the neutral ones("When did you rob the hank？" ). The idea is that if you are【C11】______, your body will reveal the truth, even if you try to【C12】______it. Your heart rate and breathing will change【C13】______as you respond to the question.

That is the theory, but psychologists have found that lie detectors are simply not【C14】______. Since most physical changes are the same across【C15】______emotions, lie detectors cannot tell【C16】______you are feeling angry, nervous or excited.【C17】______people may be tense and nervous【C18】______the whole procedure. They may react physiologically to a certain word("bank")not because they robbed it, but because they recently used a bad check. In either【C19】______, the machine will record a "lie" .

On the other hand, some practiced liars can lie【C20】______hesitation, so the reverse mistake is also common.

【C1】

A．fixed

B．designed

C．known

D．produced